List of top Physics Questions

A current $I$ flows along the length of an infinitely long, straight, thin-walled pipe. Then
A 1.0 mH inductance, a 10 $\mu F$ capacitance and a 5.0 ohm resistance are connected in series to an a.c. source. It is found that the inductor and the capacitor show equal reactances. The reactance should be nearest to
A $0.5\, kg$ ball is thrown vertically up with $14 \,m s^{-1}$. It attains a height of $8\,m$. The energy dissipated by air drag acting on the ball during ascent is
A $0.2\, k\Omega$ resistor and $15\,\mu F$ capacitor are connected in series to a $220\,V$, $50\,Hz$ ac source. The impedance of the circuit is
$^{}_{92}U^{238}$ on absorbing a neutron goes over to $^{}_{92}U^{239} .$ This nucleus emits an electron to go over to neptunium which on further emitting an electron goes over to plutonium. The resulting plutonium can be expressed as.
Clouds appear to float in air due to
A small ball of density $\rho$ is immersed in a liquid of density $(\sigma > \rho)$ to a depth h and released. The height above the surface of water up to the ball will jump is
The S.I Unit of pressure is
A body is dropped from a height of $4 \,m$ on a surface. If in collision $25\%$ of energy is lost, then the height upto which it will rise after collision is
The relationship between Young's modulus $Y$, bulk modulus $K$ and modulus of rigidity $\eta$ is
8000 identical water drops combine together, to form a big drop. Then the ratio of the final surface energy to the initial surface energy of all the drops together is.
If plane surface of a piano convex lens is silvered, then it will behave as a
A closed iron ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet is
The number of $\alpha$-particles and $\beta$-particles respectively emitted in the reaction $ {_{88}A^{196} -> _{78}B^{164}}$
Longitudinal wave can travel in
Real gas behaves as an ideal gas, under which of the following conditions ?
A projectile is projected with speed $49\,ms^{-1}$ at an angle of $30^{\circ}$ with horizontal. The time taken by the projectile to reach the highest point is
The electrical conductivity of a semiconductor increases when electromagnetic radiation of wave length shorter than $2480\, nm$ is incident on it. The band gap (in $eV$) for semiconductor is
The potential difference across the collector of a transistor, used in common emitter mode is $1.5\, V$, with the collector resistance of $3\, k\Omega$, the emitter current is $[\beta = 50]$
A horizontal disk is rotating with angular velocity $\omega $ about a vertical axis passing through its centre. A ball is placed at the centre of groove and pushed slightly. The velocity of the ball when it comes out of the groove-
A car is moving with speed $20 \, \, \text{m s}^{- 1}$ on a circular path of radius $100 \, \, \text{m}$ . Its speed is increasing at a rate of $3 \, \text{m s}^{- 2}$ . The magnitude of the acceleration of the car at that moment is
The normal reaction on a body placed in a lift moving up with constant acceleration $2 \, m \, s^{- 1}$ is $120 \, N$ . Mass of the body is (Take $g=10 \, m \, s^{- 2}$ )
A block of mass $M$ is resting on a smooth horizontal plane. One end of a uniform rope of mass $\frac{M}{4}$ is fixed to the block, which pulled it in the horizontal direction by applying a force $F$ at the other ends. The tension in the middle of the rope is
For the arrangement in the figure, the particle $M_{1}$ attached to one end of a string which moves on a horizontal table in a circle of radius $=\frac{l}{2}$ (where $l$ is the length of the string) with the constant angular speed $\omega $ . The other end of the string attached to mass $M_{2}$ which rests on a vertical rod. When the rod collapse, the acceleration of mass $M_{2}$ at that instant
$\,^{221}_{87}$Ra undergoes radiorctive decay with a half life of 4 days. The probability that a Ra nucleus will disintegrate in 8 days is