Valve Electronics Test

Result

Valve Electronics Test - 7

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Weekly Quiz Competition

Question 1
1 / -0

The amplification factor of a triode is 50. If the grid potential is decreased by 0.20V. What increase, in plate potential will keep the plate current unchanged?

A
5V

B
10V

C
0.2V

D
50V

Solution
Question 2
1 / -0

The slope of plate characteristic of a vacuum diode is 2×10⁻²mA/V. The plate resistance of diode will be

A
50 Ω

B
50 kΩ

C
500 Ω

D
500 kΩ

Solution
Question 3
1 / -0

The transconductance of a triode amplifier is 2.5 mili mho having plate resistance of 20 kΩ, amplification 10. Find the ,load resistance

A
5 kΩ

B
25 kΩ

C
20 kΩ

D
50 kΩ

Solution
Question 4
1 / -0

The amplification factor of a triode is 18 and its plate resistance is 8×10Ω. A load resistance of 104 Ω is connected in the plate circuit. The voltage gain will be

A
30

B
20

C
10

D
1

Solution
Question 5
1 / -0

The ripple factor in a half wave rectifier is

A
1.21

B
0.48

C
06

D
None of these

Solution
Question 6
1 / -0

The plate resistance of a triode is 2.5×10⁴Ω and mutual conductance is 2×10⁻³ mho. What will be the value of amplification factor

A
50

B
1.25×10⁷

C
75

D
2.25×10⁷

Solution

According to the data given in the question,

μ = r_p × gm = 2.5×10⁴×2×10⁻³= 50
Question 7
1 / -0

Plate voltage of a triode is increase from 200 V to 225 V. To maintain the plate current, change in gride voltage from 5 V to 5.75 V is needed. The amplification factor is

A
40

B
45

C
33.3

D
25

Solution

Given:-

Plate voltage of a triode is increase from 200V to 225V

Change in gride voltage from 5V to 5.75V
Question 8
1 / -0

The current in a triode at anode potential 100 V and grid potential - 1.2 V is 7.5 mA. If grid potential is changed to −2.2 V, the current becomes 5.5 mA, the value of trans conductance (g) will be

A
2 mili mho

B
3 mili mho

C
4 mili mho

D
0.2 mili mho

Solution
Question 9
1 / -0

Select the correct statement

A
In a full wave rectifier, two diodes work alternatively

B
In a full wave rectifier, two diodes work simultaneously

C
The efficiency of full wave and half wave rectifiers is same

D
The full wave rectifier is bi-directional.

Solution

A rectifier circuit whose transformer secondary is tapped to get the desired output voltage, using two diodes alternatively, to rectify the complete cycle is called as a Center-tapped Full wave rectifier circuit.
Question 10
1 / -0

In a diode value the cathode temperature must be (ϕ= work function)

A
High and ϕ should be high

B
High and ϕ should be low

C
low and ϕ should be high

D
low and ϕ should be high

Solution

In a diode value the cathode temperature must be high and ϕ should be low.