List of top Physics Questions

A particle of mass \( m \) is suspended from a point O by a string of length \( R \). It is given a velocity \( u = 3\sqrt{gR} \) at the bottom. The difference in tension at point B and at the point C is

A pipe A is connected with other pipes B and C as shown in the figure. The areas of cross-section of A, B and C are respectively \( \alpha \), \( \frac{\alpha}{2} \) and \( \frac{\alpha}{4} \). If the velocities of flow of water through A and B are 10 m/sec and 6 m/sec, respectively, then velocity of flow, \( V_c \) along C is

A uniform rod AB is suspended from a point P, at a variable distance x, from A, as shown in figure. To make the rod horizontal, a mass 'm' is suspended from its end A. Which set of variables will give a straight line when they are plotted?

The magnetic moment of an iron bar is \( M \). It is now bent in such a way that it forms an arc section of a circle subtending an angle of \( 60^\circ \) at the centre. The magnetic moment of the arc section is

A radioactive element \( {}^{242}_{92}\text{X} \) emits two \( \alpha \)-particles, one electron and two positrons. The transformed nucleus is represented by \( {}^{234}_{P}\text{Y} \). The value of \( P \) is

Two spherical soap bubbles of radii \( r_1 \) and \( r_2 \) in vacuum coalesce under isothermal condition. The newly formed bubble has a radius (\( r \)) given by

Radiation of wavelength \( \lambda \) is incident on a photocell. The fastest emitted electron has speed \( v \). If the wavelength is changed to \( \frac{3\lambda}{4} \), then the speed of the fastest emitted electron will be

A ray of light travelling in air is incident on one face of a parallel glass slab of thickness \( t \) and refractive index \( \mu \) at an angle of incidence \( i \). Total time spent by the ray inside the slab is

Which one of the following graphs represents the velocity-time (v - t) graph of a small spherical body falling in a viscous liquid?

Three blocks of masses \( m_1 = 2\text{ kg} \), \( m_2 = 3\text{ kg} \) and \( m_3 = 5\text{ kg} \) are placed on a horizontal frictionless surface and a force of \( 30\text{ N} \) pulls the system as shown below. The value of tension \( T \) will be

A person has a minimum distance of distinct vision of 50 cm. The power of lenses required to read a book at a distance of 25 cm is

The I-V characteristics graph shown below is exhibited by

A body initially at rest and sliding along a frictionless track from a height 'h' (as shown in figure) just completes a vertical circle of diameter AB = d. The height 'h' is equal to

The velocity \( v \) of a particle at time \( t \) is given by \( v = at + \frac{b}{t+c} \), where \( a \), \( b \) and \( c \) are constants. The dimension of \( a \), \( b \) and \( c \) are, respectively

The inputs to a digital circuit are as shown below. The output Y is

Two identical metal bars are heated in two different temperatures and allowed to cool in the same surroundings. Which one of the following figures correctly shows their cooling curves?

Three vectors \( \vec{a} \), \( \vec{b} \) and \( \vec{c} \) are such that \( |\vec{a}|=1 \), \( |\vec{b}|=2 \) and \( |\vec{c}|=4 \) along with \( (\vec{a} + \vec{b} + \vec{c}) = 0 \). Then, the value of \( 4\vec{a}\cdot\vec{b} + 3\vec{b}\cdot\vec{c} + 3\vec{c}\cdot\vec{a} \) will be

There is a ring of radius \( r \) having linear charge density \( \lambda \) and rotating with a uniform angular velocity \( \omega \). The magnitude of the magnetic field produced by this ring at its own centre would be (\( \mu_0 \)= permeability of air)

From a tower of height \( H \), a particle is thrown vertically upwards with a speed \( u \). The time taken by the particle to hit the ground is \( n \) times that taken by it to reach the highest point of its path. The relation between \( H \), \( u \) and \( n \) is

A uniform but time varying magnetic field is present in a circular region of radius 'R'. The magnetic field is perpendicular and into the plane of loop and the magnitude of field is increasing at a constant rate \( \alpha \). There is a straight conducting rod of length 2R placed as shown in figure. The magnitude of induced emf across the rod is

The equation of a transverse wave is \( y = y_0 \sin 2\pi\left(ft - \frac{x}{\lambda}\right) \). If the maximum particle velocity be four times that of wave velocity then

A simple pendulum of length \( l \) has a bob of mass \( m \), with a charge \( q \). On it a vertical sheet of charge with surface charge density \( \sigma \) passes through the point of suspension. At equilibrium, if the string makes an angle \( \theta \) with the vertical, then

A resistor of resistance 'R' draws power 'P' when connected to an AC source. If an inductance is now placed in series with R, such that the impedance of the circuit becomes 'Z', the power drawn will be

A square of side \( L \) lies in the \( x-y \) plane, where the magnetic field is given by \( \vec{B} = B_0(2\hat{i} + 3\hat{j} + 4\hat{k}) \) where \( B_0 \) is constant. The magnetic flux passing through the square is

A circular coil, carrying current, has radius \( R \). The distance from the centre of the coil on the axis where the magnetic induction will be \( \frac{1}{27}\text{th} \) of its value at the centre of the coil is