List of top Physics Questions

Two identical bar magnets each of magnetic moment \( M \), separated by some distance are kept perpendicular to each other. The magnetic induction at a point at the same distance \( d \) from the centre of magnets, is
\textit{( \( \mu_0 \) = permeability of free space)}
Surface density of charge on a charged conducting sphere of radius \( R \) in terms of electric intensity \( E \) at a distance \( r \) in free space is
\textit{(where \( r>R, \, \epsilon_0 \) is permittivity of free space)}
An electron (\( e \)) is revolving in a circular orbit of radius \( r \) in a hydrogen atom. The angular momentum \( M \) of the electron is
\textit{(where \( M \) = magnetic dipole moment associated with it and \( m \) = mass of the electron)}
When open pipe is closed from one end then third overtone of closed pipe is higher in frequency by 150 Hz than second overtone of open pipe. The fundamental frequency of open end pipe will be
Two small drops of mercury each of radius \( R \) coalesce to form a large single drop. The ratio of the total surface energies before and after the change is
The force acting on the electrons in hydrogen atom (Bohr’s theory) is related to the principle quantum number \( n \) as
In common emitter amplifier, input resistance is \( 1000 \, \Omega \), peak value of input signal voltage is 5 mV and \( \beta = 60 \). The peak value of output current is
Using Bohr’s quantization condition, what is the rotational energy in the second orbit for a diatomic molecule? (I = moment of inertia of diatomic molecule, \( h \) = Planck’s constant)
Two identical strings of length \( l \) and \( 2l \) vibrate with fundamental frequencies \( N \) hertz and \( 1.5N \) hertz, respectively. The ratio of tensions for smaller length to larger length is
A ray of light is incident at an angle \( i \) on one face of a prism of small angle \( A \) and emerges normally from the other surface. \( \mu \) is the refractive index of the material of the prism. The angle of incidence is
A moving body is covering distances which are proportional to the square of the time. Then the acceleration of the body is
A monoatomic gas of pressure \( P \) having volume \( V \) expands isothermally to a volume \( 2V \) and then adiabatically to a volume \( 16V \). The final pressure of the gas is
\textit{(Ratio of specific heats = \( \frac{5}{3} \))}
A solid cylinder of radius \( R \) and mass \( M \) rolls down an inclined plane of height \( h \). When it reaches the bottom of the plane, its rotational kinetic energy is
\textit{(g = acceleration due to gravity)}
The magnifying power of a telescope is high if its objective and eyepiece have respectively
An ammeter of resistance 20 \( \Omega \) gives full scale deflection when 1 mA current flows through it. What is the maximum current that can be measured by connecting 4 resistors each of 16 \( \Omega \) in parallel with the meter?
Water rises in a capillary tube of radius \( r \) upto a height \( h \). The mass of water in a capillary is \( m \). The mass of water that will rise in a capillary of radius \( \frac{r}{4} \) will be
A coil of \( n \) turns and resistance \( R \, \Omega \) is connected in series with a resistance \( \frac{R}{2} \). The combination is moved for time \( t \) second through magnetic flux \( \phi_1 \) to \( \phi_2 \). The induced current in the circuit is
In amplitude modulation,
A body is thrown from the surface of the Earth with velocity \( V \, \text{m/s} \). The maximum height above the Earth's surface up to which it will reach is
\textit{(R = radius of earth, \( g \) = acceleration due to gravity)}
Two rods of the same material and volume having circular cross-section are subjected to tension \( T \). Within the elastic limit, the same force is applied to both the rods. Diameter of the first rod is half of the second rod, then the extensions of the first rod to second rod will be in the ratio
When a small amount of impurity atoms are added to a semiconductor then generally its resistivity
The extension in a wire obeying Hooke’s law is \( x \). The speed of sound in the stretched wire is \( V \). If the extension in the wire is increased to \( 4x \), then the speed of sound in the wire is
An iron rod is placed parallel to the magnetic field of intensity 2000 \( A/m \). The magnetic flux through the rod is \( 6 \times 10^{-4} \, Wb \) and its cross-sectional area is \( 3 \, cm^2 \). The magnetic permeability of the rod in \( \frac{Wb}{A \cdot m} \) is
A charged particle is moving in a uniform magnetic field in a circular path of radius \( R \). When the energy of the particle becomes three times the original, the new radius will be
If there is a change of angular momentum from 1 J·s to 4 J·s in 4 seconds, then the torque is