List of top Physics Questions on Transistors

An electron (mass = $ 9 \times 10^{-31} $ kg, charge = $ 1.6 \times 10^{-19} $ C) moving with a velocity of $ 10^6 $ m/s enters a magnetic field. If it describes a circle of radius $ 0.1 $ m, then the strength of the magnetic field must be:

A parallel plate air capacitor of capacitance $ C $ is connected to a cell of emf $ V $ and then disconnected from it. A dielectric slab of dielectric constant $ K $, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect?

In YDSE, how many maximas can be obtained on a screen, including central maxima, on both sides of the central fringe if $ \lambda = 3000$ Å, $ d = 5000$ Å?

An $ \alpha $-particle of 10 MeV collides head-on with a copper nucleus ($ Z = 29 $) and is deflected back. The minimum distance of approach between the centers of the two is:

A force $ \mathbf{F} = \alpha \hat{i} + 3 \hat{j} + 6 \hat{k} $ is acting at a point $ \mathbf{r} = 2 \hat{i} - 6 \hat{j} - 12 \hat{k} $. The value of $ \alpha $ for which angular momentum about the origin is conserved is:

A square frame of side $ 10 $ cm and a long straight wire carrying current $ 1A $ are in the plane of the paper. Starting from close to the wire, the frame moves towards the right with a constant speed of $ 10 $ m/s (see figure). The induced EMF at the time the left arm of the frame is at $ x = 10 $ cm from the wire is:

The force between two short bar magnets with magnetic moments $ M_1 $ and $ M_2 $ whose centers are $ r $ meters apart is 8 N when their axes are in the same line. If the separation is increased to $ 2r $, the force between them is reduced to:

A given ray of light suffers minimum deviation in an equilateral prism $ P $. Additional prisms $ Q $ and $ R $ of identical shape and of the same material as $ P $ are now added as shown in the figure. The ray will now suffer:
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In an n-p-n common emitter (CE) transistor the collector current changes from 5 m A to 16 mA for the change in base current from 100 μ A and 200 μA , respectively. The current gain of transistor is Options 1. 110 2. 0.9 3. 210 4. 9

If the power and current gains of a transistor amplifier are 16500 and 100 respectively, then voltage gain is___

The purpose of a coupling capacitor in a transistor amplifier is to___

A Carnot engine has an efficiency of 50%. If the temperature of the sink is reduced by $ 40^\circ C $, its efficiency increases by 30%. The temperature of the source will be:

For a CE transistor amplifier, the audio signal voltage across the collector resistance of $ 4 \, \text{k}\Omega $ is 5V. If the current amplification factor of the transistor is 100 and the base resistance is $ 2 \, \text{k}\Omega $, then the input signal voltage is

A particle of mass $ M $ originally at rest is subjected to a force whose direction is constant but magnitude varies with time according to the relation $ F = F_0 \left[ 1 - \left( \frac{t - T}{T} \right)^2 \right] $
where $ F_0 $ and $ T $ are constants. The force acts only for the time interval $ 2T $. The velocity $ v $ of the particle after time $ 2T $ is:

For a transistor, $ \alpha $ and $ \beta $ are given as $ \alpha = \frac{I_C}{I_E} $ and $ \beta = \frac{I_C}{I_B} $. Then the correct relation between $ \alpha $ and $ \beta $ will be:

If two soap bubbles of different radii are connected by a tube:

If $ E $ and $ H $ represent the intensity of electric field and magnetizing field respectively, then the unit of $ \frac{E}{H} $ will be:

In the circuit shown in the figure, the total charge is $ 750 \, \mu C $ and the voltage across capacitor $ C_2 $ is $ 20 \, {V} $. Then the charge on capacitor $ C_2 $ is:

An ideal gas is expanding such that $ P T^3 = {constant} $. The coefficient of volume expansion of the gas is:

The de Broglie wavelength of a proton and $ \alpha $-particle are equal. The ratio of their velocities is:

Alternating current cannot be measured by a D.C. ammeter because

The typical transfer characteristics of a transistor in CE configuration is shown in figure. A load resistor of $2$ $kΩ$ is connected in the collector branch of the circuit used. The input resistance of the transistor is $0.50$ $kΩ$. The voltage gain of the transistor is ________.

Read following statements concerning electronic devices
(A)A transistor is used as rectifier
(B)A zener diode is used as a voltage regulator
(C)A not gate is a Universal Gate
(D)A transistor is used as an amplifier
(E)A photodiode is used as an oscillator
Choose the correct answer from the options given below:

For a transistor to act as a switch, it must be operated in

The electron concentration in an $n$-type semiconductor is the same as hole concentration in a $p$-type semiconductor. An external field (electric) is applied across each of them. Compare the currents in them.