List of top Physics Questions

Three concentric conducting shells carry charges +4Q on inner, –2Q on middle and +6Q on outer. The charge on inner surface of the outer shell is
Modern vacuum pumps can evacuate a vessel down to a pressure of \(4.0 \times 10^{-15}\,\text{atm}\). At room temperature (300 K), taking \(R = 8.3\,\text{J K}^{-1}\text{mol}^{-1}\) and \(N_{\text{Avogadro}} = 6 \times 10^{23}\,\text{mol}^{-1}\), the mean distance between molecules of gas in an evacuated vessel will be of the order of:
Find equivalent capacitance between points A and B. Assume each conducting plate has same dimensions and neglect the thickness of plate. It is given that \[ \frac{6A\varepsilon_0}{d}=7\,\mu F, \] where A is the area of plates.
When an electric heater is switched on, the current \(i\) is plotted against time \(t\). Taking into account the variation of resistance with temperature, which of the following best represents the resulting curve?
Temperature of body falls from 62°C to 50°C in 10 minutes. Surroundings are 26°C. The temperature after next 10 minutes will become
In the indicator diagram fig. shown of Carnot cycle Ta, Tb, Te, Td represent temperature of gas at A, B, C, D respectively. Which of the following is correct relation
A wire of variable mass per unit length is \( \mu = \mu_0 x \), hanging from the ceiling as shown in the figure. A small transverse disturbance is produced at its lower end. Find the time after which the disturbance will reach to the other end.
In the arrangement, spring constant \(k=2\) N/m, masses \(M=3\) kg and \(m=1\) kg, friction coefficient 0.1. Amplitude is 10 cm. The time period of SHM will be
If gravitational acceleration at surface is \(g\), increase in P.E. lifting mass \(m\) to height equal to half radius \(R/2\) from surface will be
A cubical ball is taken to a depth of 200 m in sea. The decrease in volume observed is 0.1%. The bulk modulus of the ball is
Acceleration versus velocity graph of a particle moving in a straight line is as shown in the graph. The corresponding velocity–time graph would be
A man wishes to cross the river flowing with velocity \(v\) making angle \(\theta\) with y direction. If he swims with speed \(u\) and width of river is \(d\), the time taken will be
Time dependence of quantity \(P=P_0 e^{-a t^2}\), dimension of a is
Four spheres of diameter 2a and mass m are placed on corners of square of side b. The moment of inertia of system about an axis through one side is
In a system, 8 kg mass is subjected to a force of 16 N along positive y axis and another 8 N along positive x axis. The angle made by acceleration of centre of mass with x axis is
A lift is moving in upward direction. The total mass of the lift and the passengers is 1600 kg. The variation of the velocity of lift is as shown in the figure. The tension in the rope at \(t = 8^{\text{th}}\) second will be
A mass \(m\) moves with velocity \(v\) and collides elastically with another identical mass. After collision, the first mass moves with velocity \(\frac{v}{\sqrt3}\) in a direction perpendicular to the initial direction of motion. Find the speed of 2nd mass after collision.

 How much charge is there on a hole? Draw the circuit symbol of p-n junction diode. 
 

A vessel contains hydrogen and nitrogen gases in the ratio 2:3 by mass. If the temperature of the mixture of the gases is 30°C, then the ratio of the average kinetic energies per molecule of hydrogen and nitrogen gases is:
The condition \( dw = dq \) holds good in the following process:
The efficiency of a Carnot engine is found to increase from 25% to 40% on increasing the temperature (\(T_1\)) of the source alone through 100 K. The temperature (\(T_2\)) of the sink is given by:
The focal length of the objective lens of a telescope is 30 cm and that of its eye lens is 3 cm. It is focused on a scale at a distance 2 m from it. The distance of the objective lens from the eye lens to see the clear image is:
The masses of a solid cylinder and a hollow cylinder are 3.2 kg and 1.6 kg respectively. Both the solid cylinder and hollow cylinder start from rest from the top of an inclined plane and roll down without slipping. If both the cylinders have equal radius and the acceleration of the solid cylinder is \( 4 { ms}^{-2} \), the acceleration of the hollow cylinder is:

Heat energy absorbed by a system going through the cyclic process shown in the figure is: 

A solid sphere of mass 50 kg and radius 20 cm is rotating about its diameter with an angular velocity of 420 rpm. The angular momentum of the sphere is: