Spectrum of a real, even signal is
a. real and even
b. imaginary and even
c. real and odd
d. imaginary and odd
Answer: a
Spectrum of a real, even signal is
a. real and even
b. imaginary and even
c. real and odd
d. imaginary and odd
Answer: a
a. real and even
b. imaginary and even
c. real and odd
d. imaginary and odd
Answer: a
A linear time invariant system is stable if its impulse response is
A linear time invariant system is stable if its impulse response is
a. summable
b. absolutely summable
c. integrable
d. absolutely integrable
Answer: b
What is the prerequisite for the divide-and-conquer approach to compute DFT (Discrete Fourier Transform) applicable?
What is the prerequisite for the divide-and-conquer approach to compute DFT (Discrete Fourier Transform) applicable?
a. The number N of data points is a prime number
b. The number N of data points is a composite number
c. The number N of data points is a Fibonacci number
d. None of the above
Answer: b
Which is a typical application of digital signal processing?
Which is a typical application of digital signal processing?
a. Noise elimination
b. Music signal processing
c. Image processing
d. All of the others
Answer: d
In a digital reproduction of an analog curve, accuracy can be increased by ________.
In a digital reproduction of an analog curve, accuracy can be increased by ________.
a. sampling the curve more often
b. sampling the curve less often
c. decreasing the number of bits used to represent each sampled value
Answer: a
The fact that sampling and amplitude modulation produce pairs of sidebands supports the concept of
The fact that sampling and amplitude modulation produce pairs of sidebands supports the concept of
a. negative frequencies.
b. Fourier square waves.
c. Gibbs' distortions.
d. all of the others.
Answer: a
Which of the following are part of the DSP core:
Which of the following are part of the DSP core:
a. Central processing unit.
b. Multiplier, accumulator, and barrel shifter.
c. Registers.
d. All of the others.
Answer: d
Using finite-precision arithmetic, one needs to be careful about
Using finite-precision arithmetic, one needs to be careful about
a. coefficient quantization errors.
b. overflow and saturation.
c. limit cycles.
d. all of the others.
Answer: d
FT{x(-n)} = _______.
FT{x(-n)} = _______.
a. X(-w).
b. X*(w).
c. X(1/w).
d. -w
Answer: a
Which of the following windows is best suited for separating two frequencies that are close to each other and have almost the same amplitudes ?
Which of the following windows is best suited for separating two frequencies that are close to each other and have almost the same amplitudes ?
a. Rectangular
b. Hamming
c. Hanning
d. All of the windows are equal for separating frequencies.
Answer: a
The Fourier transform:
The Fourier transform:
a. converts from the frequency domain to the time domain.
b. converts from the time domain to the frequency domain.
c. converts from the phasor domain to the magnitude domain.
d. is directly computed from the Z-transform.
Answer: b
With real N-Points signals, X(k) = ________ :
With real N-Points signals, X(k) = ________ :
a. X*(N-k)
b. X*(k-N)
c. X*(k)
d. X*(-k)
Answer: a
A dB value of -40 dB corresponds to a voltage ratio of
A dB value of -40 dB corresponds to a voltage ratio of
a. 100
b. 0.1
c. 1
d. 0.01
Answer: d
The convert a frequency-domain representation to a time-domain representation, one uses the
The convert a frequency-domain representation to a time-domain representation, one uses the
a. inverse FFT.
b. DFT.
c. FFT.
d. Decibel unit.
Answer: a
Convolving any signal with a delta function results in exactly the same signal.
Convolving any signal with a delta function results in exactly the same signal.
a. True
b. False
Answer: a
The following system y[n] = x[n] + 3x[n-1] is:
The following system y[n] = x[n] + 3x[n-1] is:
a. static
b. dynamic
Answer: b
The following system y[n] = nx[n] is:
The following system y[n] = nx[n] is:
a. time variant
b. time invariant
Answer: a
The basic process that's going on inside a DSP chip is:
The basic process that's going on inside a DSP chip is:
a. quantization
b. MAC
c. logarithmic transformation
d. vector calculations
Answer: b
Windows are used in FIR filter designs to
Windows are used in FIR filter designs to
a. reduce the Gibbs' phenomenon.
b. convert low-pass to high-pass.
c. convert low-pass to band-pass.
d. all of the others.
Answer: a
FIR filters are generally used in applications where
FIR filters are generally used in applications where
a. there is a need for a linear-phase filter.
b. some phase distortion is tolerable.
c. there is a need for a linear-amplitude filter.
Answer: a
The pole patterns of the signal x(n) = (1+n)u(n) are:
The pole patterns of the signal x(n) = (1+n)u(n) are:
a. Double pole at z = 1.
b. Double pole at z = 2.
c. Pole at z = 1.
d. Pole at z = 2.
Answer: a
Another name for a Brick wall filter is
Another name for a Brick wall filter is
a. Bessel.
b. Ideal filter
c. Linear.
d. Digital.
Answer: b
DFT of a finite duration sequence of length L has N point.
DFT of a finite duration sequence of length L has N point.
a. N>=L
b. N=L
c. N<=L
Answer: a
Random signals can be described by
Random signals can be described by
a. a table of data.
b. an explicit mathematical expression.
c. a well-defined rule.
d. none of the others.
Answer: d
Sine waves, cosine waves, rectangular waves, and triangular waves are all examples of
Sine waves, cosine waves, rectangular waves, and triangular waves are all examples of
a. single-frequency functions.
b. multiple-frequency functions.
c. periodic functions.
d. all of the others.
Answer: C
The choice of a filter structure depends on
The choice of a filter structure depends on
a. software complexity.
b. hardware requirement.
c. finite word length effects.
d. all of the others.
Answer: d
DSP chips store numbers as a 24-bit mantissa and an 8-bit exponent are called
DSP chips store numbers as a 24-bit mantissa and an 8-bit exponent are called
a. fixed-point processors.
b. floating-point processors.
c. adaptive processors.
d. none of the others.
Answer: b
When a sampled high-frequency signal produces the same discrete values as a low-frequency signal, the problem is called
When a sampled high-frequency signal produces the same discrete values as a low-frequency signal, the problem is called
a. Aliasing
b. Quantization
c. Component error
d. Sample and hold
Answer: a
When a sampled low-frequency signal produces the same discrete values as a high-frequency signal, the problem is called
When a sampled low-frequency signal produces the same discrete values as a high-frequency signal, the problem is called
a. Sample and hold
b. Quantization
c. Reflection
d. Aliasing
Answer: d
The following system y[n] = x[2n] is:
The following system y[n] = x[2n] is:
a. causal
b. non causal
Answer: b
Classify the following signal: weight and height measurements of a child taken every month:
Classify the following signal: weight and height measurements of a child taken every month:
a. Multi dimensional, single channel, continuous-time, analog.
b. One dimensional, single channel, continuous-time, analog.
c. One dimensional, multichannel, discrete-time, digital.
d. One dimensional, single channel, discrete-time, digital.
Answer: c
If FT{x(n)} = X(w), then FT{x(2n)} = ______.
If FT{x(n)} = X(w), then FT{x(2n)} = ______.
a. 1/2 *[X(w/2) + X((w-2pi)/2)]
b. 1/2 *[X(w/2) - X((w-2pi)/2)]
c. [X(w/2) + X((w-2pi)/2)]
d. X(w)
Answer: a
The electrical signal from a microphone is best described as
The electrical signal from a microphone is best described as
a. A quantized signal.
b. A discrete signal.
c. An aliased signal.
d. An analog or continuous signal.
Answer: d
Discrete-time signals
Discrete-time signals
a. have discrete values.
b. have discrete period.
c. are defined only at certain specific values of time.
Answer: c
The process of converting from the continuous-time domain to the discrete-time domain is called
The process of converting from the continuous-time domain to the discrete-time domain is called
a. Sampling.
b. Quantization.
c. Fourier analysis.
d. All of the others.
Answer: a
Spectrum analyzers display signals in the
Spectrum analyzers display signals in the
a. Phasor domain
b. Time domain
c. Frequency domain
d. Propogation delay domain
Answer: c
To filter long data sequences
To filter long data sequences
a. The input signal must be segmented to blocks prior to processing.
b. The DFT can be used.
c. The two methods overlap-save and overlap-add can be used.
d. All of the others.
Answer: d
What are the differences in channel allocation problem in FDMA/TDMA based system versus CDMA-based system?
What are the differences in channel allocation problem in FDMA/TDMA based system versus CDMA-based system?
a. In CDMA system, the number of possible codes indicate the number of users that can be supported so it can support more user
b. In CDMA system, the number of users are supported less than those in FDMA/TDMA
c. In FDMA/TDMA system, the number of frequencies and time slot is unlimited so it can support more users.
d. In FDMA/TDMA system, the number of frequencies and time slot is limited so it can support more users.
Answer: a
Radio signal travels from the BS to an MS along different paths-some direct, some reflected and some deflected. If the worst case difference in the path length traversed by a signal is 2 km, what is the minimum value of guard time that need to be used? Assume the signal propagation rate of 512 kbps.
Radio signal travels from the BS to an MS along different paths-some direct, some reflected and some deflected. If the worst case difference in the path length traversed by a signal is 2 km, what is the minimum value of guard time that need to be used? Assume the signal propagation rate of 512 kbps.
a. 1.415 bits
b. 2.415 bits
c. 3.415 bits
d. 4.415 bits
Answer: c
A TDMA system uses 270.833 kbps data rate to support 8 users per frame. If guard time and synchronization occupy 10:1 kbps, determine the traffic efficiency?
A TDMA system uses 270.833 kbps data rate to support 8 users per frame. If guard time and synchronization occupy 10:1 kbps, determine the traffic efficiency?
a. 60.16%
b. 70.16%
c. 80.16%
d. 90.16%
Answer: b
A TDMA system uses 270.833 kbps data rate to support 8 users per frame. What is the raw data rate provided for each user?
A TDMA system uses 270.833 kbps data rate to support 8 users per frame. What is the raw data rate provided for each user?
a. 33.85 kbps
b. 43.85 kbps
c. 53.85 kbps
d. 63.85 kbps
Answer: a
In_____, the high-rate ratio channels are spitted into multiple lower-rate subchannels that are then simultaneously transmitted over multiple orthogonal carrier frequencies.
In_____, the high-rate ratio channels are spitted into multiple lower-rate subchannels that are then simultaneously transmitted over multiple orthogonal carrier frequencies.
a. FDMA
b. TDMA
c. CDMA
d. OFDM
Answer: d
In ______, the stations use different codes to achieve multiple access.
In ______, the stations use different codes to achieve multiple access.
a. FDMA
b. TDMA
c. CDMA
d. OFDM
Answer: c
In _____, each station is allocated a time slot during which it can send data. Each station transmits its data in its assigned time slot.
In _____, each station is allocated a time slot during which it can send data. Each station transmits its data in its assigned time slot.
a. FDMA
b. TDMA
c. CDMA
d. OFDM
Answer: b
In ______, each station is allocated a band to send its data. In other words, each band is reserved for a specific station, and it belongs to the station all the time.
In ______, each station is allocated a band to send its data. In other words, each band is reserved for a specific station, and it belongs to the station all the time.
a. FDMA
b. TDMA
c. CDMA
d. OFDM
Answer: a
In _______, collisions are avoided through the use of three strategies: the interframe space, the contention window, and acknowledgments.
In _______, collisions are avoided through the use of three strategies: the interframe space, the contention window, and acknowledgments.
a. CSMA/CA
b. CSMA/CD
c. either (a) or (b)
d. both (a) and (b)
Answer: a
To avoid collisions on wireless networks, ________was invented.
To avoid collisions on wireless networks, ________was invented.
a. CSMA/CA
b. CSMA/CD
c. either (a) or (b)
d. both (a) and (b)
Answer: a
In ________, a station monitors the medium after it sends a frame to see if the transmission was successful. If so, the station is finished. If, however, there is a collision, the frame is sent again.
In ________, a station monitors the medium after it sends a frame to see if the transmission was successful. If so, the station is finished. If, however, there is a collision, the frame is sent again.
a. CSMA/CA
b. CSMA/CD
c. either (a) or (b)
d. both (a) and (b)
Answer: b
__________ augments the CSMA algorithm to detect collision.
__________ augments the CSMA algorithm to detect collision.
a. CSMA/CA
b. CSMA/CD
c. either (a) or (b)
d. both (a) and (b)
Answer: b
________ requires that each station first listen to the medium before sending.
________ requires that each station first listen to the medium before sending.
a. MA
b. CSMA
c. FDMA
d. CDMA
Answer: b
In ______, the chance of collision can be reduced if a station senses the medium before trying to use it.
In ______, the chance of collision can be reduced if a station senses the medium before trying to use it.
a. MA
b. CSMA
c. FDMA
d. CDMA
Answer: b
In ___________ methods, no station is superior to another station and none is assigned the control over another.
In ___________ methods, no station is superior to another station and none is assigned the control over another.
a. random access
b. controlled access
c. channelization
Answer: a
The vulnerable time for CSMA is the ________propagation time.
The vulnerable time for CSMA is the ________propagation time.
a. the same as
b. two times
c. three times
d. four times
Answer: a
In slotted ALOHA, the vulnerable time is ______ the frame transmission time.
In slotted ALOHA, the vulnerable time is ______ the frame transmission time.
a. the same as
b. two times
c. three times
d. four times
Answer: a
In __________, each station is forced to send only at the beginning of the time slot.
In __________, each station is forced to send only at the beginning of the time slot.
a. pure ALOHA
b. slotted ALOHA
c. CSMA /CA
d. CSMA/CD
Answer: b
In pure ALOHA, the vulnerable time is ______ the frame transmission time.
In pure ALOHA, the vulnerable time is ______ the frame transmission time.
a. the same as
b. two times
c. three times
d. four times
Answer: b
In ________ each station sends a frame whenever it has a frame to send.
In ________ each station sends a frame whenever it has a frame to send.
a. pure ALOHA
b. slotted ALOHA
c. CSMA /CA
d. CSMA/CD
Answer: a
Determine the gain in C/I in moving from an unsectored cell to one with six 60o sectors. Note the answer is independent of the number of cells in a cluster.
Determine the gain in C/I in moving from an unsectored cell to one with six 60o sectors. Note the answer is independent of the number of cells in a cluster.
a. 7.78 dB
b. 6.78 dB
c. 5.78 dB
d. 4.78 dB
Answer: a
Given a bandwidth of 50 MHz and a frequency reuse factor of 1 and RF channel size of 2.5 MHz and 48 calls per RF channel. The number of permissible calls per cell (CDMA).
Given a bandwidth of 50 MHz and a frequency reuse factor of 1 and RF channel size of 2.5 MHz and 48 calls per RF channel. The number of permissible calls per cell (CDMA).
a. 690 calls/cell
b. 790 calls/cell
c. 890 calls/cell
d. 960 calls/cell
Answer: d
Given a bandwidth of 50 MHz and a frequency reuse factor of 1 and RF channel size of 2.5 MHz and 38 calls per RF channel. Find the number of RF channels for CDMA.
Given a bandwidth of 50 MHz and a frequency reuse factor of 1 and RF channel size of 2.5 MHz and 38 calls per RF channel. Find the number of RF channels for CDMA.
a. 10 channels
b. 15 channels
c. 20 channels
d. 25 channels
Answer: c
During a busy hour, the number of calls per hour for each of the 12 cells of a cellular cluster is 2220, 1900, 4000, 1100, 1000, 1200, 1800, 2100, 2000, 1580, 1800 and 900. Assume that 75% of the car phones in this cluster are used during this period and that one call is made per phone. Find the number of customers in the system.
During a busy hour, the number of calls per hour for each of the 12 cells of a cellular cluster is 2220, 1900, 4000, 1100, 1000, 1200, 1800, 2100, 2000, 1580, 1800 and 900. Assume that 75% of the car phones in this cluster are used during this period and that one call is made per phone. Find the number of customers in the system.
a. 15200
b. 16200
c. 17200
d. 18200
Answer: b
A TDMA-based system (a cluster size N=9), has a total bandwidth of 12.5 MHz and contains 20 control channels with equal channel spacing of 30 kHz. Calculate a number of traffic channels/cell
A TDMA-based system (a cluster size N=9), has a total bandwidth of 12.5 MHz and contains 20 control channels with equal channel spacing of 30 kHz. Calculate a number of traffic channels/cell
a. 44 traffic channels/cell
b. 46 traffic channels/cell
c. 416 traffic channels/cell
d. 461 traffic channels/cell
Answer: a
One newton meter is same as
One newton meter is same as
A. one watt
B. one joule
C. five joules
D. one joule second
Answer: B
1 angstrom is equal to
1 angstrom is equal to
A. 10-8 mm
(6) 10"6 cm
C. 10"10 m
D. 10~14 m
Answer: C
Conductance : mho ::
Conductance : mho ::
A. resistance : ohm
B. capacitance : henry
C. inductance : farad
D. lumen : steradian
Answer: A
Which of the following can have negative temperature coefficient?
Which of the following can have negative temperature coefficient?
A. Compounds of silver
B. Liquid metals
C. Metallic alloys
D. Electrolytes
Answer: D
When a voltage of one volt is applied, a circuit allows one micro ampere current to flow through it. The conductance of the circuit is
When a voltage of one volt is applied, a circuit allows one micro ampere current to flow through it. The conductance of the circuit is
A. 1 n-mho
B. 106 mho
C. 1 milli-mho
D. none of the above
Answer: A
Nichrome wire is an alloy of
Nichrome wire is an alloy of
A. lead and zinc
B. chromium and vanadium
C. nickel and chromium
D. copper and silver
Answer: C
If/, R and t are the current, resistance and time respectively, then according to Joule's law heat produced will be proportional to
If/, R and t are the current, resistance and time respectively, then according to Joule's law heat produced will be proportional to
A. I2Rt
B. I2Rf
C. I2R2t
D. I2R2t*
Answer: A
A thermistor has
A thermistor has
A. positive temperature coefficient
B. negative temperature coefficient
C. zero temperature coefficient
D. variable temperature coefficient
Answer: C
With three resistances connected in parallel, if each dissipates 20 W the total power supplied by the voltage source equals
With three resistances connected in parallel, if each dissipates 20 W the total power supplied by the voltage source equals
A. 10 W
B. 20 W
C. 40 W
D. 60 W
Answer: D
The number of electrons in the outer most orbit of carbon atom is
The number of electrons in the outer most orbit of carbon atom is
A. 3
B. 4
C. 6
D. 7
Answer: B
The ratio of mass of proton to that of electron is nearly
The ratio of mass of proton to that of electron is nearly
A. 1840
B. 1840
C. 30
D. 4
Answer: A
Voltage dependent resistors are used
Voltage dependent resistors are used
A. for inductive circuits
(6) to supress surges
C. as heating elements
D. as current stabilizers
Answer: B
Voltage dependent resistors are usually made from
Voltage dependent resistors are usually made from
A. charcoal
B. silicon carbide
C. nichrome
D. graphite
Answer: C
All good conductors have high
All good conductors have high
A. conductance
B. resistance
C. reluctance
D. thermal conductivity
Answer: A
What are the materials having electrical conductivity much less than most of the metals but much greater than that of typical insulators.
What are the materials having electrical conductivity much less than most of the metals but much greater than that of typical insulators.
A. Varistors
B. Thermistor
C. Semi-conductors
D. Variable resistors
Answer: C
An open resistor, when checked with an ohm-meter reads
An open resistor, when checked with an ohm-meter reads
A. zero
B. infinite
C. high but within tolerance
D. low but not zero
Answer: B
The weight of an aluminium conductor as compared to a copper conductor of identical cross-section, for the same electrical resistance, is
The weight of an aluminium conductor as compared to a copper conductor of identical cross-section, for the same electrical resistance, is
A. 50%
B. 60%
C. 100%
D. 150%
Answer: A
A rheostat differs from potentiometer in the respect that it
A rheostat differs from potentiometer in the respect that it
A. has lower wattage rating
B. has higher wattage rating
C. has large number of turns
D. offers large number of tapping
Answer: B
Which of the following statement is correct?
Which of the following statement is correct?
A. A semi-conductor is a material whose conductivity is same as between that of a conductor and an insulator
B. A semi-conductor is a material which has conductivity having average value of conductivity of metal and insulator
C. A semi-conductor is one which con¬ducts only half of the applied voltage
D. A semi-conductor is a material made of alternate layers of conducting material and insulator
Answer: A
The condition for the validity under Ohm's law is that
The condition for the validity under Ohm's law is that
A. resistance must be uniform
B. current should be proportional to the size of the resistance
C. resistance must be wire wound type
D. temperature at positive end should be more than the temperature at negative end
Answer: A
When current flows through heater coil it glows but supply wiring does not glow because
When current flows through heater coil it glows but supply wiring does not glow because
A. current through supply line flows at slower speed
B. supply wiring is covered with insulation layer
C. resistance of heater coil is more than the supply wires
D. supply wires are made of superior material
Answer: C
Explain the V-I graph of a thermistor.
Explain the V-I graph of a thermistor.
A thermistor is a special type of resistor whose
resistance decreases as its temperature increases.
Therefore...
As the voltage increases = current increase = temperature increase = resistance decrease (only for thermistor)
Therefore, as the voltage increases on the x axis, the resistance decreases.
The gradient is the resistance. High gradient means there is less resistance.
Explain the V-I graph of a diode
Explain the V-I graph of a diode
Electricity can only pass one direction. The diode has a very big resistance in the reverse direction.
Therefore...
Diodes follows ohm's law when the current is travelling in the direction of the arrow. However, if the current is reversed the resistance of the diode is extremely high. Therefore no there is not current and voltage.
Draw the resistance - temperature graph of a thermistor
Explain the V-I graph of a filament lamp.
Explain the V-I graph of a filament lamp.
Answer: For the lamp to work the filament must heat up when an electric current passes through it, and then the filament with produce light as a result.
At high temperatures, the resistance of a thermistor is_________
At high temperatures, the resistance of a thermistor is_________
Answer: Low
At low temperatures, the resistance of a thermistor is_________
At low temperatures, the resistance of a thermistor is_________
Answer: High
In the light , the resistance of an LDR is _________
In the light , the resistance of an LDR is _________
Answer: Low
In the dark, the resistance of an LDR is _________
In the dark, the resistance of an LDR is _________
Answer: High
An increase in temperature ________ resistance. Explain way
An increase in temperature ________ resistance. Explain way
1.Increases
2.As the temperature of the material increases, the ions of the material vibrate more and this increases the number of collisions as electrons move through the wire. This increases the resistance.
An increase in thickness ________ resistance. Explain way
An increase in thickness ________ resistance. Explain way
1.decreases
2.This is because there will be more space for the electrons to flow, the chances of collision decreases
An increase in length ________ resistance. Explain way
An increase in length ________ resistance. Explain way
1.Increases
2. The longer the component, the higher the number of collision.
Describe what materials that have high resistance.
Describe what materials that have high resistance.
Answer: Wires made from iron or steel have a higher resistance.
Describe what materials that have low resistance.
Describe what materials that have low resistance.
Answer: Copper and aluminium both have a low resistance.
An increase in current ________ resistance. Explain way.
An increase in current ________ resistance. Explain way.
1.increases
2. When the current through a wire increases, the number of collisions between the electrons and the ions increases because the flow of electron increases.
What are the factors that affect resistance?
What are the factors that affect resistance?
1. Current
2.Material
3.Length
4.Thickness
5.Temperature
A component will only obey Ohm's law if the temperature is _________
A component will only obey Ohm's law if the temperature is _________
Answer: constant
If the y axis is the current and the x axis is the voltage, steep gradient indicates_______
If the y axis is the current and the x axis is the voltage, steep gradient indicates_______
Answer: low resistance
If the y axis is the current and the x axis is the voltage, a not so steep gradient indicates_______
If the y axis is the current and the x axis is the voltage, a not so steep gradient indicates_______
Answer: high resistance
If the x axis is the current and the y axis is the voltage, a not so steep gradient indicates_______
If the x axis is the current and the y axis is the voltage, a not so steep gradient indicates_______
Answer: low resistance
If the x axis is the current and the y axis is the voltage, a steep gradient indicates_______
If the x axis is the current and the y axis is the voltage, a steep gradient indicates_______
Answer: high resistance
What is the gradient of a I-V graph?
What is the gradient of a I-V graph?
Answer: resistance
Describe Ohm's Law.
Describe Ohm's Law.
The voltage is proportional to the current passing through a resistor
What is the units for resistance?
What is the units for resistance?
Answer: Ω, Ohms
What is the formula for resistance?
What is the formula for resistance?
V = I x R
Voltage = Current x Resistance
Using electrons, explain resistance?
Using electrons, explain resistance?
Answer: When electrons move through the wire, some electrons collide with the ions of the material in the wire. It is these collisions that cause electrical resistance. With each collision, some energy is lost to the wire as heat.
Which of the following materials has the least resistivity?
Which of the following materials has the least resistivity?
A. Zinc
B. Lead
C. Mercury
D. Copper
Ans:
Temperature co-efficient of resistance is expressed in terms of
Temperature co-efficient of resistance is expressed in terms of
A. ohms/°C
B. mhos/ohm°C
(e) ohms/ohm°C
D. mhos/°C
Answer: C
A nichrome wire used as a heater coil has the resistance of 2 £2/m. For a heater of 1 kW at 200 V, the length of wire required will be
A nichrome wire used as a heater coil has the resistance of 2 £2/m. For a heater of 1 kW at 200 V, the length of wire required will be
A. 80 m
B. 60 m
C. 40 m
D. 20 m
Answer: A
Two copper conductors have equal length. The cross-sectional area of one conductor is four times that of the other. If the conductor having smaller cross-sectional area has a resistance of 40 ohms the resistance of other conductor will be
Two copper conductors have equal length. The cross-sectional area of one conductor is four times that of the other. If the conductor having smaller cross-sectional area has a resistance of 40 ohms the resistance of other conductor will be
A. 160 ohms
B. 80 ohms
C. 20 ohms
D. 10 ohms
Answer: D
Ohm's law is not applicable to
Ohm's law is not applicable to
A. semi-conductors
B. D.C. circuits
C. small resistors
D. high currents
Answer: A
Three 6 ohm resistors are connected to form a triangle. What is the resistance between any two corners?
Three 6 ohm resistors are connected to form a triangle. What is the resistance between any two corners?
A. 3/2 Q
B. 6 Q
C. 4 Q
D. 8/3 Q
Answer: C
Which method can be used for absolute measurement of resistances?
Which method can be used for absolute measurement of resistances?
A. Lorentz method
B. Releigh method
C. Ohm's law method
D. Wheatstone bridge method
Answer: D
Three identical resistors are first connected in parallel and then in series. The resultant resistance of the first combination to the second will be
Three identical resistors are first connected in parallel and then in series. The resultant resistance of the first combination to the second will be
A. 9 times
B. 1/9 times
C. 1/3 times
D. 3 times
Answer: B
International ohm is defined in terms of the resistance of
International ohm is defined in terms of the resistance of
A. a column of mercury
B. a cube of carbon
C. a cube of copper
D. the unit length of wire
Answer: A
A substance whose molecules consist of dissimilar atoms is called
A substance whose molecules consist of dissimilar atoms is called
A. semi-conductor
B. super-conducto
C. compound
D. insulator
Answer: C
A field of force can exist only between
A field of force can exist only between
A. two molecules
B. two ions
C. two atoms
D. two metal particles
Answer: B
When resistance element of a heater fuses and then we reconnect it after removing a portion of it, the power of the heater will
When resistance element of a heater fuses and then we reconnect it after removing a portion of it, the power of the heater will
A. decrease
B. increase
C. remain constant
D. none of the above
Answer: B
Copper wire of certain length and resistance is drawn out to three times its length without change in volume, the new resistance of wire becomes
Copper wire of certain length and resistance is drawn out to three times its length without change in volume, the new resistance of wire becomes
A. 1/9 times
B. 3 times
(e) 9 times
D. unchanged
Answer: C
Sparking occurs when a load is switched off because the circuit has high
Sparking occurs when a load is switched off because the circuit has high
A. resistance
B. inductance
C. capacitance
D. impedance
Answer: B
Switching of a lamp in house produces noise in the radio. This is because switching operation produces
Switching of a lamp in house produces noise in the radio. This is because switching operation produces
A. arcs across separating contacts
B. mechanical noise of high intensity
C. both mechanical noise and arc between contacts
D. none of the above
Answer: A
For testing appliances, the wattage of test lamp should be
For testing appliances, the wattage of test lamp should be
A. very low
B. low
C. high
D. any value
Answer: C
Bulbs in street lighting are all connected in
Bulbs in street lighting are all connected in
A. parallel
B. series
C. series-parallel
D. end-to-end
Answer: A
Resistance of carbon filament lamp as the applied voltage increases.
Resistance of carbon filament lamp as the applied voltage increases.
A. increases
B. decreases
C. remains same
D. none of the above
Answer: B
When electric current passes through a bucket full of water, lot of bubbling is observed. This suggests that the type of supply is
When electric current passes through a bucket full of water, lot of bubbling is observed. This suggests that the type of supply is
A. A.C.
B. D.C.
C. any of above two
D. none of the above
Answer: B
In the case of direct current
In the case of direct current
A. magnitude and direction of current remains constant
B. magnitude and direction of current changes with time
C. magnitude of current changes with time
D. magnitude of current remains constant
Answer: A
Resistance of 220 V, 100 W lamp will be
Resistance of 220 V, 100 W lamp will be
A. 4.84 Q
B. 48.4 Q
C. 484 ft
D. 4840 Q
Answer: C
Two lamps 100 W and 40 W are connected in series across 230 V (alternating). Which of the following statement is correct?
Two lamps 100 W and 40 W are connected in series across 230 V (alternating). Which of the following statement is correct?
A. 100 W lamp will glow brighter
B. 40 W lamp will glow brighter
C. Both lamps will glow equally bright
D. 40 W lamp will fuse
Answer: B
In a lamp load when more than one lamp are switched on the total resistance of the load
In a lamp load when more than one lamp are switched on the total resistance of the load
A. increases
B. decreases
C. remains same
D. none of the above
Answer: B
When one leg of parallel circuit is opened out the total current will
When one leg of parallel circuit is opened out the total current will
A. reduce
B. increase
C. decrease
D. become zero
Answer: C
It becomes more difficult to remove
It becomes more difficult to remove
A. any electron from the orbit
(6) first electron from the orbit
C. second electron from the orbit
D. third electron from the orbit
Answer: D
Whether circuit may be AC. or D.C. one, following is most effective in reducing the magnitude of the current.
Whether circuit may be AC. or D.C. one, following is most effective in reducing the magnitude of the current.
A. Reactor
B. Capacitor
C. Inductor
D. Resistor
Answer: D
A glass rod when rubbed with silk cloth is charged because
A glass rod when rubbed with silk cloth is charged because
A. it takes in proton
B. its atoms are removed
C. it gives away electrons
D. it gives away positive charge
Answer: C
Two bulbs of 500 W and 200 W rated at 250 V will have resistance ratio as
Two bulbs of 500 W and 200 W rated at 250 V will have resistance ratio as
A. 4 : 25
B. 25 : 4
C. 2 : 5
D. 5 : 2
Answer: Answer: C
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