Signals and Switches MCQs : This section focuses on the "Signals and Switches". These Multiple Choice Questions (MCQs) should be practiced to improve the Signals and Switches skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
A diode placed in parallel across a relay coil serves what function?
A. to regulate input voltage
B. to protect the coil from arcing
C. to ensure most of the current passes through the coil
D. to reduce arcing across the relay contacts
A TTL totem-pole circuit is designed so that the output transistors:
A. are always on together
B. provide phase splitting
C. provide voltage regulation
D. are never on together
An indication of cutoff in an NPN bipolar transistor is that the:
A. collector current is maximum
B. collector-to-emitter voltage equals zero
C. base-to-emitter voltage equals 0.7 V
D. collector to emitter appears to be open
How long will it take to serially transmit the hexadecimal number C316 if the clock frequency is 1.5 MHz?
A. 4.69 ms
B. 4.69 s
C. 5.33 ms
D. 5.33 s
In a graphical representation of voltage versus time, ________ is displayed on the ________ axis and ________ is displayed on the ________ axis.
A. time, y, voltage, x
B. voltage, y, time, x
Internally, a computer's binary data are almost always transmitted on parallel channels, commonly referred to as the:
A. parallel bus
B. serial bus
C. data bus
D. memory bus
Normal operation of an NPN bipolar transistor requires the base to be ________ with respect to the emitter, and ________ with respect to the collector.
A. positive, negative
B. positive, positive
C. negative, positive
D. negative, negative
Serial communication can be sped up by:
A. using silver or gold conductors instead of copper
B. using high-speed clock signals
C. adjusting the duty cycle of the binary information
D. using silver or gold conductors instead of copper and high-speed clock signals
The abbreviation NO, when used with respect to electromechanical relays, stands for not operational.
The family of logic that is composed of bipolar junction transistors is ____.
The hexadecimal number 4B16 is transmitted as an 8-bit word in parallel. What is the time required for this transmission if the clock frequency is 2.25 MHz?
A. 444 ns
B. 444 s
C. 3.55 s
D. 3.55 ms
The period of a waveform is the percentage of time the signal is HIGH.
The serial format for transmitting binary information uses:
A. a single conductor
B. multiple conductors
C. infrared technology
The units for the HIGH time for a periodic wave are ________.
To forward bias a diode, a ________ potential is needed on the ________ and a ________ is needed on the ________.
A. negative, cathode, positive, anode
B. negative, anode, positive, cathode
TTL logic chips must have connections to Vcc and ground, even if all inputs and outputs are properly used and tied to valid signals.
What can a relay provide between the triggering source and the output that semiconductor switching devices cannot?
A. total isolation
C. higher current rating
D. total isolation and higher current rating
What is a disadvantage of CMOS in place of TTL?
A. It switches slower.
B. It uses less power.
C. It is smaller.
What is the advantage of using CMOS logic over TTL?
A. It switches faster.
B. It uses less power.
C. It is larger.
What is the advantage of using serial data transmission over parallel data transmission?
A. It is slower.
B. Only one pair of wires is required.
C. More people use it.
D. It is faster.
What is the minimum voltage required before a diode will allow current to flow between the cathode and the anode?
A. 0.7 V
B. 0.07 V
C. 4.3 V
D. 0.2 V
What is the period of a clock waveform that has a frequency of 15.4 kHz?
A. 649 s
B. 6.49 s
C. 64.9 s
D. 0.649 s
What is used to graphically show the time relationship between two or more digital waveforms?
A. reference diagram
B. timing diagram
C. voltage curve
D. load line
When an IC has two rows of parallel connecting pins, the device is referred to as a:
Which device(s) have almost ideal ON and OFF resistances?
A. electromechanical relays
B. manual switches
C. semiconductor devices (diodes and transistors)
D. electromechanical relays and manual switches
Why does the TTL family use a totem-pole circuit on the output?
A. It provides active pull-up.
B. It provides active pull-down.
C. It provides active pull-up and active pull-down.
Why is parallel data transmission preferred over serial data transmission for most applications?
A. It is much slower.
B. It is cheaper.
C. More people use it.
D. It is much faster.
Why, in most applications, are transistor switches used in place of relays?
A. They consume less power.
B. They are faster.
C. They are quieter and smaller.
D. all of the above
With surface-mount technology (SMT), the devices should:
A. utilize transistor outline connections
B. mount directly
C. have parallel connecting pins
D. require holes and pads