Explore topic-wise MCQs in Electronic Devices Circuits.

This section includes 16 Mcqs, each offering curated multiple-choice questions to sharpen your Electronic Devices Circuits knowledge and support exam preparation. Choose a topic below to get started.

1.

Which of the following biasing techniques are affected by thermal runaway?

A. self bias
B. collector to base bias
C. fixed bias
D. the biasing technique is identified by temperature effect
Answer» D. the biasing technique is identified by temperature effect
Discussion
2.

Thermal stability is dependent on thermal runaway which is_________

A. an uncontrolled positive feedback
B. a controlled positive feedback
C. an uncontrolled negative feedback
D. a controlled negative feedback
Answer» B. a controlled positive feedback
Discussion
3.

Thermal stability can be obtained by_________

A. shifting operating point
B. increasing power supply
C. heat sink
D. decreasing current at collector
Answer» D. decreasing current at collector
Discussion
4.

The total thermal resistance of a power transistor and heat sink is 20°C/W. The ambient temperature is 25°C and (TJ)MAX=200°C. If VCE=4V, find the maximum collector current that the transistor can carry without destruction. What will be the allowed value of collector current if ambient temperature rises to 75°C?

A. 3.67A
B. 7.56A
C. 2.19A
D. 1.56A
Answer» E.
Discussion
5.

The total thermal resistance of a power transistor and heat sink is 20°C/W. The ambient temperature is 25°C and (TJ)MAX=200°C. If VCE=4V, find the maximum collector current that the transistor can carry without destruction.

A. 3.67A
B. 7.56A
C. 2.19A
D. 4.16A
Answer» D. 4.16A
Discussion
6.

A silicon power transistor is operated with a heat sink HS-A=1.5°C/W. The transistor rated at 150W (25°C) has HJ-C=0.5°C/W and the mounting insulation has HC-S=0.6°C/W. What maximum power can be dissipated if the ambient temperature is 40°C and (TJ)MAX=200°C?

A. 70.6W
B. 61.5W
C. 37.8W
D. 56.9W
Answer» C. 37.8W
Discussion
7.

For a given transistor, the thermal resistance is 8°C/W and for the ambient temperature TA is 27°C. If the transistor dissipates 3W of power, calculate the junction temperature (TJ).

A. 51°C
B. 27°C
C. 67°C
D. 77°C
Answer» B. 27°C
Discussion
8.

THERMAL_STABILITY_IS_DEPENDENT_ON_THERMAL_RUNAWAY_WHICH_IS_________?$

A. an uncontrolled positive feedback
B. a controlled positive feedback
C. an uncontrolled negative feedback
D. a controlled negative feedback
Answer» B. a controlled positive feedback
Discussion
9.

Which_of_the_following_biasing_techniques_are_affected_by_thermal_runaway?$

A. self bias
B. collector to base bias
C. fixed bias
D. the biasing technique is identified by temperature effect
Answer» D. the biasing technique is identified by temperature effect
Discussion
10.

Thermal stability can be obtained by________?

A. shifting operating point
B. increasing power supply
C. heat sink
D. decreasing current at collector
Answer» D. decreasing current at collector
Discussion
11.

The condition to be satisfied to prevent thermal runaway?

A. ∂P<sub>C</sub>/∂T<sub>J</sub> > 1/Q
B. ∂P<sub>C</sub>/∂T<sub>J</sub> < 1/Q
C. ∂P<sub>C</sub>/∂T<sub>J</sub> > 1/Q
D. ∂P<sub>C</sub>/∂T<sub>J</sub> < 1/Q
Answer» C. ‚Äö√Ñ√∂‚àö‚Ć‚àö√°P<sub>C</sub>/‚Äö√Ñ√∂‚àö‚Ć‚àö√°T<sub>J</sub> > 1/Q
Discussion
12.

The total thermal resistance of a power transistor and heat sink is 20°C/W. The ambient temperature is 25°C and (TJ)MAX=200°C. If VCE=4V, find the maximum collector current that the transistor can carry without destruction. What will be the allowed value of collector current if ambient temperature rises to 75°C?$

A. 3.67A
B. 7.56A
C. 2.19A
D. 1.56A
Answer» E.
Discussion
13.

The total thermal resistance of a power transistor and heat sink is 20°C/W. The ambient temperature is 25°C and (TJ)MAX=200°C. If VCE=4V, find the maximum collector current that the transistor can carry without destruction.$

A. 3.67A
B. 7.56A
C. 2.19A
D. 4.16A
Answer» D. 4.16A
Discussion
14.

A silicon power transistor is operated with a heat sink HS-A=1.5°C/W. The transistor rated at 150W (25°C) has HJ-C=0.5°C/W and the mounting insulation has HC-S=0.6°C/W. What maximum power can be dissipated if the ambient temperature is 40°C and (TJ)MAX=200°C?$

A. 70.6W
B. 61.5W
C. 37.8W
D. 56.9W
Answer» C. 37.8W
Discussion
15.

Which of the following are true?

A. T<sub>J</sub>-T<sub>A</sub>=θp<sub>d</sub>
B. T<sub>J</sub>-T<sub>A</sub>=θ/p<sub>d</sub>
C. T<sub>J</sub>-T<sub>A</sub>=θ+p<sub>d</sub>
D. T<sub>J</sub>-T<sub>A</sub>=θ-p<sub>d</sub>
Answer» B. T<sub>J</sub>-T<sub>A</sub>=‚âà√≠‚Äö√†√®/p<sub>d</sub>
Discussion
16.

For a given transistor, the thermal resistance is 8°C/W and for the ambient temperature TA is 27°C. If the transistor dissipates 3W of power, calculate the junction temperature (TJ).

A. 51°C
B. 27°C
C. 67°C
D. 77°C
Answer» B. 27¬¨¬®‚Äö√†√ªC
Discussion