List of top Physics Questions

A particle starts from origin $O$ from rest and moves with a uniform acceleration along the positive $x$-axis. Identify all figures that correctly represent the motion qualitatively. (a = acceleration, v = velocity, x = displacement, t = time)

A straight rod of length $L$ extends from $x = a$ to $x = L + a$. The gravitational force is exerts on a point mass $'m'$ at $x = 0$, if the mass per unit length of the rod is $A + Bx^2$, is given by:

An electron, moving along the x-axis with an initial energy of $100\, eV$, enters a region of magnetic field $\vec{B} \, = (1.5 \times 10^{-3} T) \hat{k}$ at $S$ (See figure). The field extends between $x = 0$ and $x = 2\, cm$. The electron is detected at the point $Q$ on a screen placed $8\, cm$ away from the point $S$. The distance $d$ between $P$ and $Q$ (on the screen) is : (electron's charge = $1.6 \times 10^{-19}C.$ mass of electron = $9.1 \times 10^{-31}kg)$

Two radioactive materials $A$ and $B$ have decay constants $10 \lambda$ and $\lambda$, respectively. It initially they have the same number of nuclei, then the ratio of the number of nuclei of $A$ to that of $B$ will be $1/e$ after a time :

One plano-convex and one plano-concave lens of same radius of curvature $'R'$ but of different materials are joined side by side as shown in the figure. If the refractive index of the material of $1$ is $\mu_1$ and that of $2$ is $\mu_2$, then the focal length of the combination is :

A vertical closed cylinder is separated into two parts by a frictionless piston of mass $m$ and of negligible thickness. The piston is free to move along the length of the cylinder. The length of the cylinder above the piston is $\ell_1$, and that below the piston is $\ell_2$ , such that $\ell_1$>$\ell_2$. Each part of the cylinder contains $n$ moles of an ideal gas at equal temperature $T$. If the piston is stationary, its mass, $m$, will be given by : (R is universal gas constant and $g$ is the acceleration due to gravity)

Two identical spherical balls of mass $M$ and radius $R$ each are stuck on two ends of a rod of length $2R$ and mass $M$ (see figure). The moment of inertia of the system about the axis passing perpendicularly through the centre of the rod is :

A message signal of frequency $100\, MHz$ and peak voltage $100\, V$ is used to execute amplitude modulation on a carrier wave of frequency $300\, GHz$ and peak voltage $400\, V$. The modulation index and difference between the two side band frequencies are :

A wooden block floating in a bucket of water has $\frac{4}{5}$ of its volume submerged. When certain amount of an oil is poured into the bucket, it is found that the block is just under the oil surface with half of its volume under water and half in oil. The density of oil relative to that of water is :

In the given circuit diagram, the currents, $I_1 = 0.3\,A, I_4 = 0.8\, A$ and $I_5 = 0.4\, A$, are flowing as shown. The currents $I_2,I_3$ and $I_6$,respectively, are :

A solid sphere is rotating in free space. If the radius of the sphere is increased keeping mass same which one of the following will not be affected ?

A conducting wire frame is placed in a magnetic field which is directed into the paper. The magnetic field is increasing at a constant rate. The directions of induced current in wires $AB$ and $CD$ are

An object flying in air with velocity $\left(20\hat{i} + 25\hat{j} - 12\hat{k}\right)$ suddenly breaks in two pieces whose masses are in the ratio $1 : 5$. The smaller mass flies off with a velocity $\left(100\hat{i} + 35\hat{j} + 8\hat{k}\right)$. The velocity of the larger piece will be :

A truck is stationary and has a bob suspended by a light string, in a frame attached to the truck. The truck, suddenly moves to the right with an acceleration of a. The pendulum will tilt :-

A particle starting from rest, moves in a circle of radius 'r'. It attains a velocity of V0 m/s in the $n^{th}$ round. Its angular acceleration will be :-

A mass falls from a height 'h' and its time of fall $'l'$ is recorded in terms of time period T of a simple pendulum. On the surface of earth it is found that I = 2T. The entire set up is taken on the surface of another planet whose mass is half of that of earth and radius the same. Same experiment is repeated and corresponding times noted as t' and T'.

$\alpha$-particle consists of:

Assuming that the gravitational potential energy of an object at infinity is zero, the change in potential energy (final - initial) of an object of mass m, when taken to a height h from the surface of earth (of radius R), is given by,

The circuit diagram shown here corresponds to the logic gate,

An object kept in a large room having air temperature of 25°C takes 12 minutes to cool from 80° to 70°C. The time taken to cool for the same object from 70°C to 60°C would be nearly :

When $100 \,g$ of a liquid A at $100^{\circ}C$ is added to $50\, g$ of a liquid $B$ at temperature $75^{\circ}C$, the temperature of the mixture becomes $90^{\circ}C$. The temperature of the mixture, if $100\, g$ of liquid $A$ at $100^{\circ}C$ is added to $50\, g$ of liquid $B$ at $50^{\circ}C$, will be :

A ball falling in a lake of depth 200 m shows 0.1% decrease in its volume at the bottom. The bulk modulus of the material of the ball is

A block of mass 5 kg resting on a horizontal surface is connected by a cord, passing over a light frictionless pulley to a hanging block of mass $5\, kg$. The coefficient of kinetic friction between the block and the surface is 0.5. Tension in the cord is : $(g = 9.8 \,m/sec^2)$

The temperature coefficient of resistance of a wire is 0.00125 °C\(^{-1}\). At 300 K, its resistance is 1 \(\Omega\). At what temperature the resistance of the wire will be 2 \(\Omega\)?

A physicist works in a laboratory where the magnetic field is 2 T. She wears a necklace enclosing area 0.01 m\(^2\) in such a way that the plane of the necklace is normal to the field and is having a resistance \(R = 0.01\ \Omega\). Because of power failure, the field decays to 1 T in time \(10^{-3}\) s. Then what is the total heat produced in her necklace?