List of top Physics Questions

The capacitance of a parallel plate capacitor is 400 pF. It is connected to an ac source of 100 V having an angular frequency 100 rad s$^{-1}$. If the rms value of the current is 4 μA, the displacement current is:

How far should an object be from a concave spherical mirror of radius 36 cm to form a real image one-ninth its size?

A 4 kg stone is attached to a steel wire being whirled at a constant speed of $ 12 $ m/s in a horizontal circle. The wire is 4 m long with a diameter of 2 mm, and Young’s modulus is $ 2 \times 10^{11} $ Nm$^2$. The strain in the wire is:

For a $30^\circ$ prism, when a ray of light is incident at an angle $60^\circ$ on one of its faces, the emergent ray passes normal to the other surface. Then the refractive index of the prism is:

A diatomic gas does a work of $ \frac{Q}{4} $ when a heat of $ Q $ is supplied to it. Then the molar heat capacity of the gas is:

Two particles each of mass $m$ are separated by a distance $d$. If the mass of one of the particles is doubled without changing the distance between the two particles, then the shift in the position of the center of mass is

The relation between time $ t $ and displacement $ x $ is $ t = \alpha x^2 + \beta x $, where $\alpha$ and $\beta$ are constants. If $ \nu $ is the velocity, the retardation is:

A photoelectron emitted when a light of wavelength 2480 $\mathring{A}$ falls on a metal, enters a uniform magnetic field of $ \frac{1}{4} \times 10^{-5} $ T perpendicular to it and moves in a circular path of maximum radius 1 m. The work function of the metal is nearly:

If the potential difference across $PQ$ is 4V, the potential difference across $A$ and $B$ in the given figure is:

The motion of a particle is given by $X = a \cos t$, $Y = a \sin t$ and $Z = t$. The trajectory traced by the particle as a function of time is:

If $ S_1 $, $ S_2 $, and $ S_3 $ are the tensions at liquid-air, solid-air and solid-liquid interfaces respectively, and $ \theta $ is the angle of contact at the solid-liquid interface, then

Four identical particles each of mass 'm' are kept at the four corners of a square of side 'a'. If one of the particles is removed, the shift in the position of the centre of mass is:

For a gas in a thermodynamic process, the relation between internal energy (U), the pressure (P), and the volume (V) is given by: \[ U = 3 + 1.5PV \] The ratio of the specific heat capacities of the gas at constant volume and constant pressure is:

When $ Q $ amount of heat is supplied to a monatomic gas, the work done by the gas is $ W $. When $ Q_1 $ amount of heat is supplied to a diatomic gas, the work done by the gas is $ 2W $. Then $ Q:Q_1 $ is:

A boy standing on a platform observes the frequency of a train horn as it passes by. The change in the frequency noticed as the train approaches and recedes from him with a velocity of 108 km/h (speed of sound in air = 330 m/s) is:

A block of mass 2 kg is tied to one end of a 2 m long metal wire of 1.0 mmÂ² area of cross-section and rotated in a vertical circle such that the tension in the wire is zero at the highest point. If the maximum elongation in the wire is 2 mm, the Young's modulus of the metal is:

A body thrown vertically upwards from the ground reaches a maximum height ‘h’. The ratio of the kinetic and potential energies of the body at a height 40\% of h from the ground is

A conductor of length 1.5 m and area of cross-section $ 3 \times 10^{-5} \, \text{m}^2 $ has electrical resistance of 15 $ \Omega $. The current density in the conductor for an electric field of 21 $ \text{V/m} $ is.

A metal target with atomic number $ Z = 46 $ is bombarded with a high-energy electron beam. The emission of X-rays from the target is analyzed. The ratio $ r $ of the wavelengths of the $ K_\alpha $-line and the cutoff is found to be $ r = 2 $. If the same electron beam bombards another metal target with $ Z = 41 $, the value of $ r $ will be:

An object is placed at a distance of 18 cm in front of a mirror. If the image is formed at a distance of 4 cm on the other side, then the focal length, nature of the mirror and nature of the image are respectively:

A wave along a string has the following equation $ y = 0.02 \sin [30t – 4.0x] $ m. The speed of the wave is:

A drop of water of radius 0.01 m is falling through a medium whose density is 1.21 kg/m$^3$ and co-efficient of viscosity $ \eta = 1.8 \times 10^{-5} \, \text{Ns/m}^2 $. Then the terminal velocity of the drop is:

At temperature 'T', the 'effective' speed of gaseous hydrogen molecules (molecular weight = 2) is equal to that of oxygen molecules (molecular weight = 32) at 47°C. The value of 'T' is:

A glass bulb of volume 400 cm$^3$ is connected to another bulb of volume 200 cm$^3$ by means of a tube of negligible volume. The bulbs contain dry air. They are both at a common temperature and pressure of 20°C and 1.000 atm. The larger bulb is immersed in steam at 100°C; the smaller, in melting ice at 0°C. The final common pressure is:

A sphere of 3 cm radius acts like a black body. It is in equilibrium with its surrounding and absorbs 30 kW of power radiated to it from surroundings. The temperature of the sphere is $ \sigma = 5.67 \times 10^{-8} \, \text{W/m}^2\text{K}^4 $. What is the temperature of the sphere?