List of top Physics Questions

In semiconductors at room temperature,
A sphere, a cube and a thin circular plate all made of same material and having the same mass are heated to same temperature of $200^\circ$C. On these are left in a room.
Considering earth to be a sphere of radius $R$ having uniform density $\rho$, then value of acceleration due to gravity $g$ in terms of $R,\rho$ and $G$ is
A solenoid of length $0.4$ m and having $500$ turns of wire carries a current $3$ A. A thin coil having $10$ turns of wire and radius $0.1$ m carries a current $0.4$ A. The torque produced to hold the coil in middle of solenoid with its axis perpendicular to the axis of the solenoid is $(\mu_0=4\pi\times10^{-7}$ SI units, $\pi^2=10$, $\sin90^\circ=1)$
If the radius of the first Bohr orbit is $r$, then the de Broglie wavelength of the electron in the $4^{\text{th}}$ orbit is
The temperature of a gas is $-68^\circ$C. To what temperature should it be heated, so that the r.m.s. velocity of the molecules becomes doubled?
A combination of two thin lenses in contact have power $+10$D. The power reduces to $+6$D when the lenses are $0.25$ m apart. The power of individual lenses is
A body is said to be opaque to the radiation if $(a,r,t)$ are coefficient of absorption, reflection and transmission respectively.
In a thermodynamic system, $\Delta U$ represents the increase in internal energy and $dW$ the work done by the system. Then correct statement is
A string of length $L$ fixed at one end carries a body of mass $m$ at the other end. The mass is revolved in a circle in horizontal plane making angle $\theta$ with vertical. The angular frequency of the body is $\omega$. The tension in the string is
The reciprocal of the total effective resistance of LCR a.c. circuit is called
The electric field intensity on the surface of a solid charged sphere of radius 'r' and volume charge density '$\rho$' is ($\epsilon_0 =$ permittivity of free space)
A progressive wave is given by $Y = 12 \sin(5t - 4x)$. On this wave, how far apart are two points having a phase difference of $90^\circ$?
For a purely inductive or a purely capacitive circuit, the power factor is
A wire of length 3 m connected in the left gap of a meter-bridge balances 8$\Omega$ resistance in the right gap at a point, which divides the bridge wire in the ratio 3: 2. The length of the wire corresponding to resistance of 1$\Omega$ is
Which of the following combination of 7 identical capacitors each of $2\,\mu F$ gives a capacitance of $\frac{10}{11}\,\mu F$?
For a common emitter configuration, if '$\alpha$' and '$\beta$' have their usual meanings, the incorrect relation between '$\alpha$' and '$\beta$' is
On a dry road, the maximum speed of a vehicle along a circular path is $V$. When the road becomes wet, the maximum speed becomes $\frac{V}{2}$. If the coefficient of friction of the dry road is $\mu$, then that of the wet road is
A simple pendulum of length 'l' and a bob of mass 'm' is executing S.H.M. of small amplitude 'A'. The maximum tension in the string will be ($g =$ acceleration due to gravity)
Frequency of the series liit of Balmer series of hydrogen atom in terms of Rydberg's constant (R) and velocity of light (c) is
A horizontal wire of mass 'm', length 'l' and resistance 'R' is sliding on the vertical rails on which uniform magnetic field 'B' is directed perpendicular. The terminal speed of the wire as it falls under the force of gravity is ($g =$ acceleration due to gravity)
A particle moves around a circular path of radius 'r' with uniform speed 'V'. After moving half the circle, the average acceleration of the particle is
The diffraction fringes obtained by a single slit are of
A string is stretched between two rigid supports separated by 75 cm. There are no resonant frequencies between 420 Hz and 315 Hz. The lowest resonant frequency for the string is
A straight wire carrying a current (I) is turned into a circular loop. If the magnitude of the magnetic moment associated with it is 'M', then the length of the wire will be