List of top Physics Questions

A wire of length \( L \) meter carrying current \( i \) ampere is bent in the form of a circle. The magnitude of its magnetic moment in SI units is:
The current I drawn from the 5 volt source will be:
A ray of light passes through four transparent media with refractive index \(n_1, n_2, n_3, n_4\) as shown in the figure. The surfaces of all media are parallel. If the emergent ray ST is parallel to the incident ray PQ, we must have:
A liquid drop of radius \(R = 0.1 \, \text{m}\) having surface tension \(S = \frac{0.01}{4\pi} \, \text{N/m}\) divides itself into \(n\) identical drops. In the process, the total change in the surface energy \(\Delta U = 10^{-4} \, \text{J}\). The value of \(n\) is
A point object is placed at a distance of 25 cm from a thin plano-convex lens of focal length 20 cm. The plane surface of the lens is now silvered. The image created by the system is at:
A particle moves in a circle of radius \( R \). In half the period of revolution its displacement and distance covered respectively are:
The work function of a given metal is 4 eV. The longest wavelength of light that can cause photoelectron emission from this metal is:
The temperature of an ideal gas is increased from 75 K to 300 K. If at 75 K the r.m.s. velocity of the gas molecules is \(v\), at 300 K it becomes:
The efficiency of a Carnot engine operating between a reservoir and an sink is \( \eta \). If the temperature of the reservoir is increased by 50% and that of the sink is decreased by 50%, the new efficiency will be:
A system goes from state a to b along the path abc, when 20 kJ of heat flows into the system and the system does 7.6 kJ of work. If the system is returned back from b to a along the curved path bca due to a work of 5 kJ done on it, then
For a straight wire carrying steady current in the vertically upward direction as shown below
The dimension of force constant is
Two bodies (A and B) of masses 7 kg and 3 kg are attached to each other in the following way. If a force of 100 N is applied on A along the x direction, the force on A on B will be
Four closed surfaces and corresponding charge distributions are shown below. The respective electric fluxes through the surfaces \( S_1, S_2, S_3, S_4 \) are \( \Phi_1, \Phi_2, \Phi_3, \Phi_4 \). Then, which of the following is correct?
In a Doppler effect experiment, initially an observer and the source are moving towards each other with equal speeds. The observed frequency in this case is found to be \( f_0 \). The observed frequency once they cross each other is found to be \( f' \). If \( f \) is the frequency at the source, \( f' \) is equal to:
Consider a viscous fluid having uniform density \( \rho \) and coefficient of viscosity \( \eta \). Two solid spheres with radius \( R_1 \) and \( R_2 \) fall into this liquid and acquire terminal velocities of \( V \) and \( 8V \) respectively. If the densities of the two spheres are \( 2\rho \) and \( 3\rho \) respectively, then \( R_1 \) is equal to \( R_2 \)?
Consider two radioactive materials A and B. When A decays into 6.25 percent of its original amount, B decays into 25 percent of its original amount. The ratio of their decay constants \( \lambda_A \) and \( \lambda_B \) is:
Two very long, straight, and insulated wires are kept at a 90° angle from each other in the x-y plane as shown in the figure. These wires carry equal currents of magnitude \( I \), whose directions are shown in the figure. The net magnetic field at point P will be:
At temperature \( T \), the probability of ideal gas molecules with mass \( m \) having speed \( v \) is given by \( P(v) \). Two quantities \( I_1 \) and \( I_2 \) are defined in terms of \( P(v) \) as follows:
\[ I_1 = \int_0^\infty P(v) v^3 \, dv \quad \text{and} \quad I_2 = \int_0^\infty P(v) v \, dv \] Which of the following relationship is true?
1 gm of ice at 0°C is mixed with 1 gm of water at 100°C. At thermal equilibrium, the temperature of the mixture will be:
The ratio of specific heats \( \frac{C_P}{C_V} \) in terms of degrees of freedom (n) is given by:
A series R-C combination is connected to an AC voltage of angular frequency \( \omega = 1000 \) rad/s. If the impedance of the RC circuit is \( R/\sqrt{2} \), the time constant (in milliseconds) of the circuit is:
A transverse wave is described by the equation \( y = A \sin \left( 2 \pi \left( \frac{r}{\lambda} - \frac{t}{T} \right) \right) \). The maximum particle velocity is equal to four times the wave velocity if:
A pulse of light of duration 50 ns is absorbed completely by a small object initially at rest. Power of the pulse is 60 mW and speed of light is \( 3 \times 10^8 \) m/s. The final momentum of the object is:
A block of mass 300 g is kept stationary on a smooth inclined plane by applying a minimum horizontal force \( F = \sqrt{a} \, N \) as shown in the figure. The value of \( a \) is (Take \( g = 10 \, \text{m/s}^2 \)):