List of top Physics Questions asked in KEAM

The oscillating magnetic field in a plane electromagnetic wave is given by \(B_y = (8 \times 10^{-6}) \sin[2 \pi \times 10^{11} t + 200 \pi x] \) tesla. Then the wavelength of the electromagnetic wave (in cm) is:

An electric appliance draws 3A current from a 200 V, 50 Hz power supply. The amplitude of the supply voltage is nearly:

When an \( \alpha \) particle and a proton are projected into a perpendicular uniform magnetic field, they describe circular paths of the same radius. The ratio of their respective velocities is:

A charged particle will continue to move in the same direction in a region, where \(E\) - Electric field, \(B\) - Magnetic field:

The y-intercept of the graph between the terminal voltage \(V\) with load resistance \(R\) along \(y\) and \(x\) – axis, respectively, of a cell with internal resistance \(r\), as shown, is:

Magnitude of drift velocity per unit electric field is known as:

If the number of electron-hole pairs per cm\(^3\) of an intrinsic Si wafer at temperature 300 K is \(1.1 \times 10^{10}\) and the mobilities of electrons and holes at 300 K are 1500 and 500 cm\(^2\) per volt, second, respectively, then the conductivity of the Si wafer at this temperature (in \(\mu\)mho cm\(^{-1}\)) is nearly:

A spherical metal shell \( A \) of radius \( R_A \) and a solid metal sphere \( B \) of radius \( R_B \) (\( R_B<R_A \)) are kept far apart and each is given charge \( +Q \). If they are connected by a thin metal wire and \( Q_A \) and \( Q_B \) are the charge on \( A \) and \( B \), respectively, then:

The electric field due to an infinitely long thin wire with linear charge density \( \lambda \) at a radial distance \( r \) is proportional to:

The ratio of the magnitudes of electrostatic force between an electron and a proton separated by a distance \( r \) to that between a proton and an alpha particle separated by the same distance \( r \) is:

A tuning fork vibrating at 300 Hz, initially in air, is then placed in a trough of water. The ratio of the wavelength of the sound waves produced in air to that in water is (Given that the velocity of sound in water and in air at that place are 1500 m/s and 350 m/s respectively):

Ratio between the frequencies of the third harmonics in the closed organ pipe and open organ pipe of the same length is:

A string of length \( L \) is fixed at both ends and vibrates in its fundamental mode. If the speed of waves on the string is \( v \), then the angular wave number of the standing wave is:

The kinetic energy of 3 moles of a diatomic gas molecules in a container at a temperature \( T \) is same as that of kinetic energy of \( n \) moles of monoatomic gas molecules in another container at the same temperature \( T \). The value of \( n \) is:

According to equipartition principle, the energy contributed by each translational degree of freedom and rotational degree of freedom at a temperature T are respectively (\( k_B = \text{Boltzmann constant} \)):

Two similar metallic rods of the same length \( l \) and area of cross section \( A \) are joined and maintained at temperatures \( T_1 \) and \( T_2 \) (\( T_1>T_2 \)) at one of their ends as shown in the figure. If their thermal conductivities are \( K \) and \( \frac{K}{2} \) respectively. The temperature at the joining point in the steady state is: