List of top Physics Questions

In an oscillator, for sustained oscillations, Barkhausen criterion is $A\beta$ equal to ($A =$ voltage gain without feedback, $\beta =$ feedback factor)

A particle moves along a circle of radius ?$r$? with constant tangential acceleration. If the velocity of the particle is ?$?$? at the end of second revolution, after the revolution has started then the tangential acceleration is

A bottle has an opening of radius $a$ and length $b$. A cork of length $b$ and radius $(a+ \Delta a)$ where $(\Delta a < < a)$ is compressed to fit into the opening completely (See figure). If the bulk modulus of cork is $B$ and frictional coefficient between the bottle and cork is $\mu$ then the force needed to push the cork into the bottle is :

A modulated signal $C_m(t)$ has the form $C_m(t)=30$ sin $300 \pi t + 10$ (cos $200 \pi t -$ cos $400 \pi t$). The carrier frequency $f_{c}$, the modulating frequency (message frequency) $f_{\omega}$, and the modulation index $\mu$ are respectively given by :

A student measures the time period of $100$ oscillations of a simple pendulum four times. The data set is $90\, s, 91\, s, 95\, s$ and $92\, s$. If the minimum division in the measuring clock is $1 \,s$, then the reported mean time should be :

A and B are two parallel sided transparent slabs of refractive indices n$_1 $and n$_2$ respectively. A ray is incident at an angle $\theta$ on the surface of separation of A and B, and after refraction from B into air grazes the surface of B. Then

Hysteresis loops for two magnetic materials $A$ and $B$ are given below : These materials are used to make magnets for electric generators, transformer core and electromagnet core. Then it is proper to use :

Identify the semiconductor devices whose characteristics are given below, in the order $(a), (b), (c), (d)$ :

A satellite is revolving in a circular orbit at a height ' $h$' from the earth's surface (radius of earth $R ; h < < R$). The minimum increase in its orbital velocity required, so that the satellite could escape from the earth?s gravitational field, is close to : (Neglect the effect of atmosphere.)

A pendulum clock loses $12\,s$ a day if the temperature is $40^{\circ}C$ and gains $4\,s$ a day if the temperature is $20^{\circ}C$. The temperature at which the clock will show correct time, and the co-efficient of linear expansion $(\alpha)$ of the metal of the pendulum shaft are respectively :

A ball is thrown from a point $A$ with a speed $u$ at an angle $\theta$ with the horizontal. If $g$ is the acceleration due to gravity, the total time taken for it to reach a point $B$ on the same horizontal plane is

Two cars are in a race. The white car passed the finishing point with a velocity $ v\, ms^{-1} $ more and took time $ t\, s $ less than the red car. If both the cars start from rest and travel with constant accelerations $ a_w $ , and $ a_r $ respectively, $ \frac{v}{t} $ is given

A particle moving with an initial velocity $ u\, ms^{-1} $ is retarded by a force at the rate of $ a = - k \sqrt v $ . where $ K $ is a positive constant and $ v $ is the instantaneous velocity. The particle comes to rest in a time given by

A particle moves with a uniform speed $ v $ and time period $ T $ in a circular path of radius $ r $ . If the speed of the particle is doubled, its new time period is

Choose the wrong statement

A given sample of an ideal gas occupies a volume $V$ at a pressure $P$ and absolute temperature $T$. The mass of each molecule of the gas is $m$. Which of the following gives the density of the gas ?

The kinetic energy of a particle executing simple harmonic motion is $ 1/6^{th} $ of its maximum value at a distance of $ 5 \,cm $ from its equilibrium position. The amplitude of its motion is

In a moving coil galvanometer, the coil having $ 500 $ turns and an average area of $ 4 \,cm^{2} $ carries a current of $ 0.1 \,A $ and is set parallel to a magnetic field with a torque of $ 0.15\, N \,m $ . The strength of the magnetic field is

An organ pipe open at both ends has fundamental frequency $ f $ in air. If the pipe is dipped vertically in water such that $ 1/4^{th} $ of its length is inside water, then the fundamental frequency of the air column in it is

The pair of rigid bodies with mass M and radius R, having the moment of inertia $\frac{MR^{2}}{2}$ can be

The operating point of transistor amplifier should be in

For a thin lens with radii of curvatures and $ R_{1} $ and $ R_{2} $ , refractive index $ n $ and focal length $ f $ , the factor $ \left(\frac{1}{R_{1}}-\frac{1}{R_{2}}\right) $ is equal to

The electric flux passing through $a$ cube of side $ a $ , which holds a charge $ q $ at one of its corners is

The angle between the linear momentum and angular momentum of a particle moving along a circle is

The distance of closest approach for an alpha nucleus of velocity $ v $ bombarding a stationary heavy nucleus target of charge $ Ze $ is directly proportional to