(C) The thermionic emission current $I$ is given by Richardson-Dushman equation: $I = AT^2 e^{-\phi/kT}$,where $A$ is a constant,$T$ is the absolute t

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If the temperature of the filament is doubled,then the thermionic current will nearly be four times.

(C) The thermionic emission current $I$ is given by Richardson-Dushman equation: $I = AT^2 e^{-\phi/kT}$,where $A$ is a constant,$T$ is the absolute temperature,$\phi$ is the work function,and $k$ is the Boltzmann constant.Since $I \propto T^2$,if the temperature $T$ is doubled $(T' = 2T)$,the new current $I'$ becomes $I' \propto (2T)^2 = 4T^2$.Therefore,the thermionic current becomes nearly four times the original value.Thus,option $C$ is correct.

Class 12 Physics Semiconductor Electronics Valve Electronics

Easy

In a triode valve,which of the following statements is correct?

A
If the grid voltage is zero,then the plate current will be zero.
B
If the temperature of the filament is doubled,then the thermionic current will also be doubled.
C
If the temperature of the filament is doubled,then the thermionic current will nearly be four times.
D
At a definite grid voltage,the plate current varies with plate voltage according to Ohm’s law.

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Class 12

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Chapter

Semiconductor Electronics

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Valve Electronics

$A$ triode has a mutual conductance of $2 \times 10^{-3} \text{ mho}$ and an amplification factor of $50$. The anode is connected through a resistance of $25 \times 10^3 \, \Omega$ to a $250 \, \text{V}$ supply. The voltage gain of this amplifier is

Medium

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The linear portions of the characteristic curves of a triode valve give the following readings. The plate resistance is ....... $\Omega$.
$V_g$ (volt) $0$ $-2$ $-4$ $-6$
$I_p$ (mA) for $V_p = 150$ $V$ $15$ $12.5$ $10$ $7.5$
$I_p$ (mA) for $V_p = 120$ $V$ $10$ $7.5$ $5$ $2.5$

Difficult

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The grid in a triode valve is used

Easy

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Before the saturation state of a diode,at plate voltages of $400 \, V$ and $200 \, V$,the currents are $i_1$ and $i_2$ respectively. The ratio $i_1/i_2$ will be:

Easy

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$A$ change of $0.8 \,mA$ in the anode current of a triode occurs when the anode potential is changed by $10 \,V$. If $\mu = 8$ for the triode,then what change in the grid voltage would be required to produce a change of $4 \,mA$ in the anode current?

Medium

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$V_g$ (volt)	$0$	$-2$	$-4$	$-6$
$I_p$ (mA) for $V_p = 150$ $V$	$15$	$12.5$	$10$	$7.5$
$I_p$ (mA) for $V_p = 120$ $V$	$10$	$7.5$	$5$	$2.5$

In a triode valve,which of the following statements is correct?

Similar Questions

$A$ triode has a mutual conductance of $2 \times 10^{-3} \text{ mho}$ and an amplification factor of $50$. The anode is connected through a resistance of $25 \times 10^3 \, \Omega$ to a $250 \, \text{V}$ supply. The voltage gain of this amplifier is

The linear portions of the characteristic curves of a triode valve give the following readings. The plate resistance is ....... $\Omega$.$V_g$ (volt)$0$$-2$$-4$$-6$$I_p$ (mA) for $V_p = 150$ $V$$15$$12.5$$10$$7.5$$I_p$ (mA) for $V_p = 120$ $V$$10$$7.5$$5$$2.5$

The grid in a triode valve is used

Before the saturation state of a diode,at plate voltages of $400 \, V$ and $200 \, V$,the currents are $i_1$ and $i_2$ respectively. The ratio $i_1/i_2$ will be:

$A$ change of $0.8 \,mA$ in the anode current of a triode occurs when the anode potential is changed by $10 \,V$. If $\mu = 8$ for the triode,then what change in the grid voltage would be required to produce a change of $4 \,mA$ in the anode current?

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The linear portions of the characteristic curves of a triode valve give the following readings. The plate resistance is ....... $\Omega$.
$V_g$ (volt) $0$ $-2$ $-4$ $-6$
$I_p$ (mA) for $V_p = 150$ $V$ $15$ $12.5$ $10$ $7.5$
$I_p$ (mA) for $V_p = 120$ $V$ $10$ $7.5$ $5$ $2.5$