List of top Physics Questions

The maximum number of TV signals that can be transmitted along a co-axial cable is:
Output of the following logic circuit is:
logic circuit
The metal which has the highest work function in the following is:
The graph of \( \ln \left( \frac{R}{R_0} \right) \) versus \( \ln A \), where \( R \) is the radius of a nucleus, \( A \) its mass number, and \( R_0 \) a constant, is:
If the average power per unit area delivered by an electromagnetic wave is \( 9240 \, \text{Wm}^{-2} \), what is the amplitude of the magnetic field in the wave?
A beam of light with intensity \( 10^5 \, \text{Nm}^{-2} \) and cross-sectional area \( 20 \, \text{cm}^2 \) is incident on a fully reflective surface at an angle of \( 45^\circ \). Find the force exerted by the beam on the surface.
For a hydrogen atom, the energy of a stationary electron is given by \( E_n = -\frac{13.6}{n^2} \, \text{eV} \). The energy required to excite the electron to the second excited state and to the ionized state are:
An electromagnetic wave travels along the z-axis. At a certain point in space, the electric field is \( 8.7 \, \text{Vm}^{-1} \) along the x-axis. What is the magnitude of the magnetic field along the y-axis?
A coil of inductance \( 0.1 \, \text{H} \) and resistance \( 110 \, \Omega \) is connected to an AC source of \( 110 \, \text{V}, 350 \, \text{Hz} \). What is the phase difference between the voltage maximum and the current maximum?
A capacitor \( C_1 = 1\, \mu\text{F} \) is charged using a 9 V battery. It is then disconnected and connected to capacitors \( C_2 = 2\, \mu\text{F} \) and \( C_3 = 3\, \mu\text{F} \) as shown. Find the charge on \( C_3 \) after equilibrium is reached.
A capacitor C1 = 1µF is charged using a 9 V battery
Two positive charges of 10 \( \mu \text{C} \) and 12 \( \mu \text{C} \) are 10 cm apart. What is the work done in bringing them 6 cm closer?
Two infinite wires are placed at \( x = -2 \, \text{cm} \) and \( x = 1 \, \text{cm} \) along the y-axis, each carrying current upward. An electron is fired from the origin at \( 45^\circ \) to the x-axis with speed \( U \). The force on the electron at the moment of launch is:
(\( B_0 \) is the field at origin due to the wire at \( x = 1 \, \text{cm} \))
Two electrons \( e_1 \) and \( e_2 \), both having mass \( m \) and charge \( q \), are projected perpendicular to a magnetic field \( B \). If the kinetic energy of \( e_1 \) is twice that of \( e_2 \), what is the relation between their rotation frequencies \( f_1 \) and \( f_2 \)?
A compass needle oscillates 20 times per minute at a location with dip \( 45^\circ \) and magnetic field \( B_1 \). It oscillates 30 times per minute at another location where dip is \( 30^\circ \) and field is \( B_2 \). Find the ratio \( \frac{B_1}{B_2} \).
Current density in a cylindrical wire of radius \( R \) varies with radial distance as \( \beta (r + r^2) \). What is the current through the shaded section (sector angle \( \pi/6 \)) of the wire as shown in the figure?
Current density in a cylindrical wire of radius R
A cell supplies currents of 1 A and 0.5 A through resistors of 2.5 \( \Omega \) and 10 \( \Omega \), respectively. The internal resistance of the cell is:
Electrostatic force between two identical charges placed at a distance \( r \) is \( F \). A slab of width \( \frac{r}{5} \) and dielectric constant 9 is inserted between them. Then, the new force between the charges is:
A ray is incident from a medium of refractive index 2 to another with refractive index 1. The critical angle is:
A body is suspended from a string of length 1 m and mass 2 g. The mass of the body required to produce a fundamental frequency of 100 Hz in the string is (Take \( g = 10 \, \text{ms}^{-2} \))
An electric dipole with dipole moment \( 5 \times 10^{-7} \, \text{Cm} \) is in an electric field of \( 2 \times 10^4 \, \text{NC}^{-1} \) at an angle of \( 60^\circ \) with the direction of the field. The torque acting on the dipole is:
A Carnot engine operates between a source and sink. The efficiency of the engine is 40\% and the sink temperature is \( 27^\circ \text{C} \). If the efficiency is to be increased to 50\%, then by how much should the source temperature be increased?
A car engine has a power of 20 kW and runs for 1 hour. If the thermal efficiency is 40\% and ambient temperature is 300 K, then what is the energy generated by fuel combustion?
The number of vibrational degrees of freedom for a diatomic molecule is:
A cone with half the density of water is floating in water as shown. It is depressed down by a small distance \( \delta \ll H \) and released. The frequency of SHM of the cone is:
A cone with half the density of water is floating in water
Same tension is applied to four wires made of the same material. The elongation is maximum in which wire?