Valve Electronics Test

Result

Valve Electronics Test - 6

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Weekly Quiz Competition

Question 1
1 / -0

Before the saturation state of a diode at the plate voltage of 400 V and 200 V respectively the currents are i₁ and i₂ respectively. The ratio i₁/i₂ will be

A
√2/4

B
2√2/1

C
2/1

D
1/2

Solution

Before saturation region, linear region comes. In linear region i_p∝ V_p
Question 2
1 / -0

The value of plate current in the given circuit diagram will be

A
3 mA

B
8 mA

C
13 mA

D
18 mA

Solution

The value of plate current i = 1.125 − 1.112 = 0.013 A = 13 mA
Question 3
1 / -0

Costing of strontium oxide on Tungsten cathode in a value is good for thermionic emission because

A
Work function decreases

B
Work function increases

C
Conductivity of cathode increases

D
Cathode can be heated to high temperature

Solution

Costing of strontium oxide on Tungsten cathode in a value is good for thermionic emission because work function decreases.
Question 4
1 / -0

Following is the relation between current and voltage I=AT²e^qt/VL then value of V will be

A
V/KT

B
kV/T

C
kT/V

D
V T / K

Solution

Comparing the given equation with standard equation
Question 5
1 / -0

Which one is correct relation for thermionic emission

A
J = AT^1/2/e^−ϕ/kT

B
J = AT²/e^−ϕ/kT

C
J = AT^3/2 /e^−ϕ/kT

D
J = AT⁻² /e^−ϕ/2kT

Solution

In the case of thermionic emission we observe emitted electrons from a metal due to its high temperature. The higher the temperature, the higher will be the current of escaping electrons. This temperature induced electron flow is called thermionic emission

J = AT²/e^−ϕ/kT
Question 6
1 / -0

When plate voltage in diode valve is increased from 100V to 150V. Then, plate increases from 7.5 mA to 12 mA, then dynamic plate resistance will be

A
10 kΩ

B
11 kΩ

C
15 kΩ

D
11.1 kΩ

Solution

The dynamic resistance of a diode valve is the ratio of small change in plate voltage to the small change in plate current i.e.
Question 7
1 / -0

In a diode value, the state of saturation can be obtained easily by

A
High plate voltage and high filament current

B
Low filament current and high plate voltage

C
Low plate voltage and high cathode temperature

D
High filament current and high plate voltage

Solution

In a diode value, the state of saturation can be obtained easily by low filamenr current and high plate voltage.
Question 8
1 / -0

Plate resistance of two triode value is 2 kΩ and 4 kΩ amplification factor each of the values is 40.The ratio of voltage amplification, when used with 4 kΩ load resistance, will be

A
10

B
4/3

C
3/4

D
16/3

Solution

We know that Voltage amplification is given as;
Question 9
1 / -0

Diode is used as a/an

A
moculator

B
rectifier

C
oscillator

D
amplifier

Solution
Question 10
1 / -0

Which of the following does not vary with plate or grid voltages

A
g

B
R

C
μ

D
Each of them varies

Solution

We know that g_m = μr_p and I_p= K (V_P + μV_G)^3/2

From the formulae we can see grid voltage don not depend on g , R and μ.