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Test: Power Diode

20 Questions MCQ Test Power Electronics | Test: Power Diode

Description

Attempt Test: Power Diode | 20 questions in 15 minutes | Mock test for Electrical Engineering (EE) preparation | Free important questions MCQ to study Power Electronics for Electrical Engineering (EE) Exam | Download free PDF with solutions

QUESTION: 1

An ideal power diode must have

A.
low forward current carrying capacity
B.
large reverse breakdown voltage
C.
high ohmic junction resistance
D.
high reverse recovery time

Solution:

Large reverse breakdown voltage is desirable whereas others will increases the losses.

QUESTION: 2

To make a signal diode suitable for high current & high voltage carrying applications with minimum losses, ________

A.
a lightly doped n layer is grown between the two p & n layers
B.
a heavily doped n layer is grown between the two p & n layers
C.
a lightly doped p layer is grown between the two p & n layers
D.
a heavily doped p layer is grown between the two p & n layers

Solution:

The above process simply the one used to manufacture power diodes.

QUESTION: 3

Power diode is __________

A.
a three terminal semiconductor device
B.
a two terminal semiconductor device
C.
a four terminal semiconductor device
D.
a three terminal analog device

Solution:

It has two terminals anode and cathode same as that of a ordinary diode. In fact, a power diode is nothing but a signal diode with a extra layer.

QUESTION: 4

The V-I Characteristics of the diode lie in the

A.
1st & 2nd quadrant
B.
1st & 3rd quadrant
C.
1st & 4th quadrant
D.
Only in the 1st quadrant

Solution:

First in the forward region & Third in the reverse biased mode.

QUESTION: 5

Which of the following is true in case of a power diode with R load?

A.
I grows almost linearly with V
B.
I decays almost linearly with V
C.
I is independent of V
D.
I initial grows than decays

Solution:

R load therefore V and I are linear and in phase.

QUESTION: 6

A diode is said to be reversed biased when the

A.
cathode is positive with respect to the anode
B.
anode is positive with respect to the cathode
C.
cathode is negative with respect to the anode
D.
both cathode & anode are negative

Solution:

K is positive w.r.t the A when the device is reversed biased.

QUESTION: 7

A diode is said to be forward biased when the

A.
cathode is positive with respect to the anode
B.
anode is positive with respect to the cathode
C.
anode is negative with respect to the anode
D.
both cathode & anode are positive

Solution:

A is positive w.r.t the K when the device is forward biased.

QUESTION: 8

In case of an ideal power diode, the leakage current flows from

A.
anode to cathode
B.
cathode to anode
C.
in both the directions
D.
leakage current does not flow

Solution:

Leakage current does not flow in IDEAL diode.

QUESTION: 9

The peak inverse current IP for a power diode is given by the expression

A.
I_P=t + di/dt
B.
I_P=t * log ⁡i
C.
I_P=t * di/dt
D.
I_P=t * ∫ t*i dt

Solution:

The leakage current is the reveres recovery time (t) into the rate of change of current.

QUESTION: 10

A power diode with small softness factor (S-factor) has

A.
small oscillatory over voltages
B.
large oscillatory over voltages
C.
large peak reverse current
D.
small peak reverse current

Solution:

Peak reverse current is independent of S-factor smaller the value of S-factor larger the oscillatory over voltage.

QUESTION: 11

If V & I are the forward voltage & current respectively, then the power loss across the diode would be

A.
V/I
B.
V² I²
C.
I² V
D.
VI

Solution:

Simply power (P) is voltage into current i.e. VI

QUESTION: 12

The power loss in which of the following cases would be the maximum?

A.
When both V & I are minimum
B.
When both V & I are maximum
C.
When only V is maximum
D.
When only I is maximum

Solution:

P=VI Hence, it would be maximum when both V and I are maximum.

QUESTION: 13

Even after the forward current reduces to zero value, a practical diode continues to conduct in the reverse direction for a while due to the

A.
resistance of the diode
B.
high junction temperature
C.
stored charges in the depletion region
D.
none of the mentioned

Solution:

Due to the stored charges during the earlier current flow, even when the current reduces to zero due to some structural properties of the device, the device takes time to sweep out the stored charges.

QUESTION: 14

For a p-n junction diode, the peak inverse current & the reverse recovery time are dependent on

A.
inverse voltage
B.
forward Voltage
C.
di/dt
D.
all of the above mentioned

Solution:

It only depends upon the number stored charges which depends upon the rate of change of current.

QUESTION: 15

In an AC-DC converter, a diode might be used as a

A.
voltage source
B.
phase angle controller
C.
freewheeling Diode
D.
filter

Solution:

In converters diodes are used to feed the energy back to the load in case of an inductive load.

QUESTION: 16

When the p-n junction diode is forward biased, the width of the depletion region __________

A.
increases
B.
decreases
C.
remains Constant
D.
increases than Decreases

Solution:

When forward biased depletion layer decreases & finally it collapses to allow the current flow.

QUESTION: 17

When the p-n junction diode is reversed biased, the width of the depletion region __________

A.
increases
B.
decreases
C.
remains Constant
D.
none of the above mentioned

Solution:

When reverse biased depletion layer increases until the breakdown value is reached.

QUESTION: 18

In case of a practical p-n junction diode, the rise in the junction temperature ___________

A.
decreases the width of the depletion region
B.
increases the barrier potential
C.
increases the width of the depletion region
D.
width of the depletion region increases but the barrier potential remains constant

Solution:

The rise in temperature excites the charges, which go & recombine with the charges in the depletion region decreasing its width. Higher the temperature, lesser is the E.M.F required to turn on the device.

QUESTION: 19

In the equilibrium state, the barrier potential across a unbiased silicon diode is _________