Test: Power Transistors


20 Questions MCQ Test Power Electronics | Test: Power Transistors


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This mock test of Test: Power Transistors for Electrical Engineering (EE) helps you for every Electrical Engineering (EE) entrance exam. This contains 20 Multiple Choice Questions for Electrical Engineering (EE) Test: Power Transistors (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Power Transistors quiz give you a good mix of easy questions and tough questions. Electrical Engineering (EE) students definitely take this Test: Power Transistors exercise for a better result in the exam. You can find other Test: Power Transistors extra questions, long questions & short questions for Electrical Engineering (EE) on EduRev as well by searching above.
QUESTION: 1

Which of the following devices does not belong to the transistor family?

Solution:

GTO is gate turn off transistor, it belongs to the Thyristor family. All the other devices belong to the transistor family.

QUESTION: 2

 A power transistor is a

Solution:

 It has three layers p-n-p or n-p-n forming two p-n junctions.

QUESTION: 3

In a power transistor, ____ is the controlled parameter.

Solution:

The collector current is the controlled parameter.

QUESTION: 4

A power transistor is a _________ device.

Solution:

 Power transistor is simply many BJT’s connected in series parallel on a single silicon chip for power applications. It is a three terminal, bipolar, current controlled device.

QUESTION: 5

 In a power transistor, _________ is the controlling parameter.

Solution:

The base current controls the collector current. Hence, the base current Ib is the controlling parameter.

QUESTION: 6

In a power transistor, the IB vs VBE curve is

Solution:

The B-E junction of a BJT resembles a p-n junction diode, hence the curve.

QUESTION: 7

For a power transistor, if the base current IB is increased keeping VCE constant, then

Solution:

Ic is directly proportional to Ic.

QUESTION: 8

The forward current gain α is given by

Solution:

Collector current by emitter current is the current gain, its value is close to one but never greater than.

QUESTION: 9

The value of β is given by the expression

Solution:

Collector current by the base current is beta, its value is in the range 50 to 300.

QUESTION: 10

A power BJT is used as a power control switch by biasing it in the cut off region (off state) or in the saturation region (on state). In the on state

Solution:

When base-emitter & base-collector junctions are forward biased only than both the p-n junctions are forward biased and the device is on.

QUESTION: 11

 For a power transistor, if the forward current gain α = 0.97, then β = ?

Solution:

 Use the relation α = β/(β+1).

QUESTION: 12

The power electronics devices have a very high efficiency because

Solution:

They are efficient due to their higher transition speeds.

QUESTION: 13

For a power transistor, which of the following relations is true?

Solution:

 Practically speaking Ie = Ib+Ic. Ie is the highest as it is the sum of the collector and base currents. The base current is the smallest.

QUESTION: 14

High frequency operation of any device is limited by the

Solution:

Lower the switching losses higher the frequency of operation of the device.

QUESTION: 15

The instantaneous power loss during the delay time of a transistor is given by

Solution:

 During the delay time only the collector current flows & base to emitter voltage is zero.

QUESTION: 16

For a power transistor, the average power loss during the delay time can be given by the equation

Solution:

During the delay time only, the collector current flows & base to emitter voltage is zero. Hence the average power can be found, simply by integrating it over the total delay time & dividing by the base time period.

QUESTION: 17

A 1mv of i/p gives an output of 1V, the voltage gain as such would be

Solution:

1V/1mv = 1000.

QUESTION: 18

Which of the following relations is true for a BJT?

Solution:

The collector & emitter current differ only by the base current, which is very very small.

QUESTION: 19

Choose the correct statement

Solution:

Unlike the thyristor devices, all the transistor family devices remain in the conducting state as long as the firing pulses are applied. This is a very important property of the transistor devices.

QUESTION: 20

 Let’s say that a transistor is operating at the middle of the load line, then a decrease in the current gain would

Solution:

The current gain would decreases the collector current, shifting the Q point below.

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