This set of Embedded Systems Multiple Choice Questions & Answers (MCQs) focuses on “Power Controls”
1. Which of the following can be used for providing high gain?
a) transistor
b) darlington transistor pair
c) resistor
d) capacitor
View Answer
Explanation: The darlington pair of transistors can provide high gain than a single transistor. This is one of the method used to avoid voltage mismatches that the system produces. By using high gain transistors the voltage mismatches can be reduced upto a limit.
2. Which devices have high drive capability?
a) transistor
b) fet
c) buffer pack
d) darlington amplifier
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Explanation: The buffer pack is used to avoid the voltage mismatches which possesses a high drive capacity and it can also provide high drive currents than the normal logic outputs.
3. Which of the following is used to switch heavy loads?
a) fet
b) transistor
c) buffer pack
d) darlington pair
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Explanation: The field effect transistor can be used to provide a very high effective gain and hence they can be used to switch heavy loads easily from a logic device. These are also voltage controlled transistors.
4. Which allows the switching of DC motor by using two outputs and four FETs?
a) transistor
b) H bridge
c) darlington pair
d) buffer pack
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Explanation: The H bridge can be created by using several switches which allows a DC motor to be switched on and reversed in the direction. The switching can be done by using two outputs and four FETs.
5. Which of the following is used to create H bridge?
a) switches
b) led
c) capacitor
d) inductor
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Explanation: The H bridge can be created by using several switches. This allows a DC motor to be switched on and reversed in the direction and the switching of DC motor can be done by using two outputs and four FETs.
6. Which of the following allows voltage reversing?
a) H bridge
b) Relays
c) LEDs
d) LCDs
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Explanation: The H bridge is used in controlling DC motors or any other loads which need voltage reversing.
7. Which devices are used as indicators in a digital system?
a) LCD
b) LED
c) Varactor diode
d) Gunn diode
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Explanation: The light emitting diodes are used as indicators in the digital system and can be directly driven from a logic output.
8. How is the biasing done in LEDs?
a) forward bias
b) no bias
c) supply voltage
d) reverse bias
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Explanation: The LEDs will light up only when the diode reverse breakdown is achieved. It is usually about 2 to 2.2V.
9. Which of the following determines the brightness of LEDs?
a) current
b) voltage
c) resistance
d) conductance
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Explanation: The current drive determines the brightness of the LEDs and it is usually associated with a current limiting resistor in series with the LED to prevent the overheating.
10. Which of the following is a current limiting device?
a) voltage
b) current
c) buffer
d) inductor
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Explanation: A buffer can be used as a current limiting device. Similarly, a transistor can also be used as a current limiting device.
11. Which of the following can switch the current by a make or break contact?
a) transistor
b) relay
c) buffer
d) fet
View Answer
Explanation: The relays are a kind of switching power in which the logic signal is used to energise the relay. The relay contacts are break or make accordingly and helps in switching the current.
12. Which of the following generates a back EMF?
a) relay
b) buffer
c) transistor
d) FET
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Explanation: The relay generates a back voltage across its terminals when the logic output switches from a high to low state.
13. Which of the following is used to avoid the back EMF in the relay?
a) resistor
b) capacitor
c) inductor
d) diode
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Explanation: In order to get rid of the back EMF which is generated by the relay a diode is connected across the terminals which operate in the reverse bias so that nothing can harm the relay.
14. Which of the following can provide a speed control technique in the DC motor interfacing?
a) PCM
b) DPCM
c) ADPCM
d) PWM
View Answer
Explanation: The pulse width modulation can provide a speed control technique in the DC motor interfacing by changing its mark/space ratio.
15. Which of the following possesses some loops for providing timing functions?
a) hardware
b) software
c) timer
d) counter
View Answer
Explanation: In the software system, certain loops perform the timing functions. A program is created to switch the motor on and it will start counting through a delay loop. When the count is finished, the motor is switched off. In the second delay loop, it can determine the motor-off period.
Sanfoundry Global Education & Learning Series – Embedded System.
To practice all areas of Embedded System, here is complete set of 1000+ Multiple Choice Questions and Answers.
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