List of top Physics Questions

When a slab of insulating material 4 mm thick is introduced between the plates of a parallel plate capacitor of separation 4 mm, it is found that the distance between the plates has to be increased by 3.2 mm to restore the capacity to its original value. The dielectric constant of the material is______.
Fill in the blank with the correct answer from the options given below.

A vernier callipers has 20 divisions on the vernier scale, which coincides with 19^th division on the main scale. The least count of the instrument is 0.1 mm. One main scale division is equal to ____mm.

Two parallel plate capacitors, each of capacitance 40 µF, are connected in series. The space between the plates of one capacitor is filled with a material of dielectric constant K = 4. The equivalent capacitance of the system would be:

A 200-turn circular coil of area 10³cm² rotates at 60 revolutions per minute in a uniform magnetic field of 0.02 T perpendicular to the axis of rotation of the coil. The maximum voltage induced in the coil is:

Two charged metallic spheres with radii $R_1$ and $R_2$ are brought in contact and then separated. The ratio of final charges $Q_1$ and $Q_2$ on the two spheres respectively will be _____.
Fill in the blank with the correct answer from the options given below

If the energy of incident radiation is increased by $25\%$, the kinetic energy of the photoelectrons emitted increases from 0.6 eV to 0.9 eV. The work function of the metal is:

A conducting wire of length L, uniform area of cross-section A, and material having n free electrons per unit volume offers a resistance R to the flow of current. m and e are the mass and charge of an electron, respectively. If τ is the mean free time of the electrons in the conductor, the correct formula for resistance R is:

A magnetic dipole aligned parallel to a uniform magnetic field requires a work of W units to rotate it through 60°. The torque exerted by the field on the dipole in this new position is:

A particle is moving along x-axis with its position ($ x $) varying with time ($ t $) as:
$ x = \alpha t^4 + \beta t^2 + \gamma t + \delta. $
The ratio of its initial velocity to its initial acceleration, respectively, is:

Two charged particles, placed at a distance d apart in vacuum, exert a force F on each other. Now, each of the charges is doubled. To keep the force unchanged, the distance between the charges should be changed to_____
Fill in the blank with the correct answer from the options given below.

A uniform metal wire of length $l$ has 10 Ω resistance. Now this wire is stretched to a length $2l $ and then bent to form a perfect circle. The equivalent resistance across any arbitrary diameter of that circle is :

Two infinitely long straight parallel conductors carrying currents $I_1$ and $I_2$ are held at a distance d apart in vacuum. The force F on a length L of one of the conductors due to the other is _______.
Fill in the blank with the correct answer from the options given below

A parallel plate capacitor of capacitance $ 12.5 \, \text{pF} $ is charged by a battery connected between its plates to a potential difference of $ 12.0 \, \text{V} $. The battery is now disconnected and a dielectric slab ($ \varepsilon_r = 6 $) is inserted between the plates. The change in its potential energy after inserting the dielectric slab is ______ $ \times 10^{-12} \, \text{J} $.

At which temperature will the r.m.s. velocity of a hydrogen molecule be equal to that of an oxygen molecule at $ 47^\circ \text{C} $?

A capacitor and a coil with resistance R are in series and connected to a 6 V AC source. By varying the frequency of the source, a maximum current of 600 mA is observed. If the same coil is now connected to a cell of emf 6 V and internal resistance of 2 ohms, the current through it will be:

If the momentum of an electron is changed by P, then the de Broglie wavelength associated with it changes by $1\%$. The initial momentum of the electron will be:

The position of the centre of mass of the uniform plate as shown in the figure is:

The Power $ P $ radiated from an accelerated charged particle is given by $ P \propto \left( \frac{q a}{c^n} \right)^m $, where $ q $ is the charge, $ a $ is the acceleration, and $ c $ is the speed of light in vacuum. From dimensional analysis, the value of $ m $ and $ n $ respectively are:

Figure shows a part of an electric circuit. The potentials at points $ a, b, \text{and} \, c $ are $ 30 \, \text{V}, 12 \, \text{V}, \, \text{and} \, 2 \, \text{V} $, respectively. The current through the $ 20 \, \Omega $ resistor will be:

An electric bulb rated 200 V - 100 W is connected to a 160 V power supply. The power consumed by it would be:

A conducting ring of radius r is placed in a varying magnetic field perpendicular to the plane of the ring. If the rate at which the magnetic field varies is x, the electric field intensity at any point of the ring is________.
Fill in the blank with the correct answer from the options given below.

Figure shows a rectangular frame situated in a constant magnetic field. A wire BC of length $1\text{ m}$ is moved out with velocity $4\text{ m/s}$. Magnetic field strength is $0.15\text{ T}$. Force acting on the wire $BC$ is

In a biprism experiment, fifth dark fringe is obtained at a point. A thin transparent film of refractive index '$\mu$' is placed in one of the interfering paths. Now $7^{\text{th}}$ bright fringe is obtained at the same point. If '$\lambda$' is the wavelength of light used, the thickness of film is equal to

The height at which the acceleration due to gravity becomes $\frac{g}{4}$ in terms of $R$ is [ $R = \text{the radius of the earth}$ ]

A photon and an electron have an equal energy ' $\text{E}$ '. The ratio of wavelength ' $\lambda_\text{p}$ ' of photon to that of electron ' $\lambda_\text{e}$ ' is proportional to