List of top Physics Questions

A metal rod of length 1 m at 20°C is made up of a material of coefficient of linear expansion \( 2 \times 10^{-5} \, \text{°C}^{-1} \). The temperature at which its length is increased by 1 mm is:
A fluid has stream line flow through a horizontal pipe of variable cross-sectional area. Then:
If \( n \) small identical liquid drops, each having terminal velocity \( v \), merge together, then the terminal velocity of the bigger drop is:
The slope of the graph plotted between the square of the time period of a planet \( T^2 \) and the cube of its mean distance from the sun \( r^3 \) is:
The value of escape velocity \( v_e \) for a planet depends on:
When a vehicle moving with kinetic energy \( K \) is stopped in a distance \( d \) by applying a stopping force \( F \), the relation between \( F \) and \( K \) is given by:
A machine gun fires a bullet of mass 25 g with a velocity of 1000 ms\(^{-1}\). If the man holding the gun can exert a maximum force of 100 N on the gun, the maximum number of bullets that he can fire per second is:
If the slope of the velocity-time graph of a moving particle is zero, then its acceleration is:
The length of the second's hand in a watch is 1 cm. The magnitude of the change in the velocity of its tip in 30 seconds (in cm/s) is:
Add \( 2.7 \times 10^{-5} \) to \( 4.5 \times 10^{-4} \) with due regard to significant figures
When a diode is reverse biased
An intrinsic semiconductor at \( T = 0 \, {K} \) behaves like
The half-life period of a radioactive element is 2 days. If \( \frac{1}{32} \) part of the initial amount remains undecayed after a time \( t \), then the value of \( t \) in days is
The electron concentration \( n_e \) and hole concentration \( n_h \) in semiconductor are related to the number of intrinsic charge concentration \( n_i \) as
In a nuclear fusion process, the masses of the fusing nuclei are \( M_A \) and \( M_B \). Then the mass of the product nucleus \( M_C \) is related to \( M_A \) and \( M_B \) as
The particle which is expected to be emitted along with \( Y \) in the following nuclear reaction is \[ { }^{198}_{80}X \rightarrow { }^{197}_{79}Y + ? \]
The number of de Broglie waves associated with Bohr electron when it completes one revolution in its third orbit is
Young’s double-slit experiment is carried out by using green, red and blue lights, one at a time. The fringe widths recorded are \( \beta_G \), \( \beta_R \) and \( \beta_B \) respectively. Then
Electromagnetic waves of frequency \( 5 \times 10^{14} \, {Hz} \) lie in the
In an LCR series resonance circuit driven by the alternating voltage \( V = V_0 \sin \omega t \), inductance \( L = 1 \, \mu H \), capacitance \( C = 1 \, \mu F \) and resistance \( R = 1 \, k\Omega \). The resonant angular frequency (in rad/s) is:
An alternative form of Biot-Savart's law is
The ratio of radii of the circular paths of a proton and a deuteron when projected perpendicular to the direction of a uniform magnetic field with the same speed is

The energy stored in the capacitor after closing the key K is 

Two like charges kept in air medium experience a force \( F \), when they are separated by a certain distance \( r \). When the same charges are kept in a dielectric medium at the same distance of the separation, the force between them is 0.5F. The dielectric constant of the medium is
If \( E \) is the electric field intensity between the plates of a charged parallel plate capacitor, energy stored per unit volume in it is (permittivity of free space = \( \epsilon_0 \))