Electronic Devices and Communication Systems Test

Result

Electronic Devices and Communication Systems Test - 4

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Weekly Quiz Competition

Question 1
1 / -0

A full wave rectifier is fed with AC mains of frequency 50 Hz. What is the fundamental frequency of ripple in the output current?

A
25 Hz

B
50 Hz

C
75 Hz

D
100 Hz

Solution

Positive part of wave is retained and negative part of wave is made positive.
Therefore, number of pulses/second = frequency x 2 = 100 Hz(pulses/second = fundamental frequency of the ripple)
Question 2
1 / -0

An oscillator is an amplifier with

A
a large gain

B
negative feedback

C
positive feedback

D
no feedback

Solution

An oscillator is an amplifier with positive feedback.
Question 3
1 / -0

Which of the following statements is not true?

A
The resistance of intrinsic semiconductor decreases with increase of temperature.

B
Doping pure Si with trivalent impurities gives p-type semiconductor.

C
The majority carriers in n-type semiconductors are holes.

D
A p-n junction can act as a semiconductor diode.

Solution

The resistance of intrinsic semiconductor decreases with increase of temperature. Doping pure Si with trivalent impurities gives p-type semiconductor where as doping with pentavalent impurity gives n-type semiconductor. The majority carriers in n-type semiconductors are electrons. A p-n junction can act as a semiconductor diode.
Question 4
1 / -0

Compared to CB amplifier, CE amplifier has

A
low input resistance

B
low output resistance

C
low current amplification

D
infinite current amplification
Solution
Among the different configurations of transistors CC (common collector), CE (common emitter) and CB (common base), the common emitter (CE) configuration transistor has the following advantages.
- High input resistance
- Low output resistance
- More efficiency
- More current amplification
- More voltage amplification