# Electronic Devices and Circuits Questions and Answers – The CE Short Circuit Current Frequency Response

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “The CE Short Circuit Current Frequency Response”.

1. What is the value of input resistance in the CE short circuit current frequency response model?
a) hoe
b) hib
c) hic
d) hie

Explanation: The input resistance of a common emitter (CE) amplifier can be expressed in terms of hybrid parameters in the CE short circuit current frequency response model. The input resistance is universally expressed as hie. This is also the same for approximate as well as exact hybrid models.

2. How do we calculate the value of IC in the CE short circuit current frequency response model?
a) IC = hre × IB
b) IC = -hre × IB
c) IC = hfe × IB
d) IC = -hfe × IB

Explanation: The collector current of a common emitter (CE) amplifier can be expressed in terms of hybrid parameters in the CE short circuit current frequency response model. It is expressed as the product of hfe × IB. This is the same for approximate hybrid models as well.

3. What is the value of current gain in the CE short circuit current frequency response model?
a) hfe
b) -hfe
c) hre
d) –hre

Explanation: The current gain of a common emitter (CE) amplifier can be expressed in terms of hybrid parameters in the CE short circuit current frequency response model. The current gain hfe is the forward transfer characteristics and is used to calculate the current gain in common emitter amplifiers.

4. What is the value of voltage gain in the CE short circuit current frequency response model?
a) hfe × RL / hre
b) –hfe × RL / hre
c) hfe × RL / hie
d) –hfe × RL / hie

Explanation: The voltage gain of a common emitter (CE) amplifier can be expressed in terms of hybrid parameters in the CE short circuit current frequency response model. The voltage gain is equal to -hfe × RL / hie where, RL is load resistance, hie is input resistance and -hfe is the current gain.

5. What is the magnitude of voltage generated at emitter circuit of a CE short circuit current frequency response model?
a) hre × hfe / Ib × RL
b) hre × hfe × Ib × RL
c) hre × hfe / IC × RL
d) hre × hfe × IC × RL

Explanation: The magnitude of voltage generated at emitter circuit of a common emitter (CE) amplifier can be expressed in terms of hybrid parameters in the CE short circuit current frequency response model. The magnitude of voltage generated is equal to hre × hfe × Ib × RL where, RL is load resistance and Ib is the base current.

6. What is the value of output resistance in the CE short circuit current frequency response model?
a) ∞
b) 0
c) hic
d) hie

Explanation: The output resistance in a simplified common emitter hybrid model is calculated as the ratio of collector voltage over collector current while VS is equal to zero and RL is omitted. Due to this configuration IC is equal to zero and hence output resistance is infinite.

7. What is the value power gain in the CE short circuit current frequency response model?
a) AV – AI
b) AV + AI
c) AV × AI
d) AV / AI

Explanation: The power gain in a simplified common emitter hybrid model is calculated as the product of voltage gain and power gain. It is expressed as AV × AI. It can also be further simplified as AI2 × RL / Ri, where RL is load resistance and Ri is input resistance.

8. What is the value of overall current gain in the CE short circuit current frequency response model while considering RS?
a) AI × IB / IS
b) AI × IC / IS
c) AI × IS / IC
d) AI × IS / IB

Explanation: The current gain in a simplified common emitter hybrid model while considering RS is calculated as the product of current gain without external parameters and the ratio of base current and external applied current. It is expressed as AI × IB / IS. Where, IS is the external applied current on the amplifier.

9. What is the value of overall voltage gain in the CE short circuit current frequency response model while considering RS?
a) VB / VS
b) VC / VS
c) VB × VS
d) VC × VS

Explanation: The overall voltage gain in a simplified common emitter hybrid model while considering RS is calculated as ratio of base voltage over the applied external voltage. It is expressed as VB / VS. Where, VS is the external applied voltage on the amplifier.

10. We use CE short circuit current frequency response models to obtain approximate values.
a) True
b) False

Explanation: It is more practical to calculate the approximate values of voltage and current gains instead of computing the exact values of a common emitter amplifier circuit. We use a simplified common emitter hybrid model to obtain these approximate values without reducing the accuracy.

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