Explore topic-wise MCQs in Electronic Devices and Circuits Questions and Answers.

This section includes 4 Mcqs, each offering curated multiple-choice questions to sharpen your Electronic Devices and Circuits Questions and Answers knowledge and support exam preparation. Choose a topic below to get started.

1.

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
2.

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
3.

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
4.

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