List of top Physics Questions

A device which converts electrical energy into mechanical energy is
An elliptical cavity is carved within a perfect conductor. A positive charge q is placed at the centre of the cavity. The points A and B are on the cavity surface as shown in the figure.then
Biaxial crystal among the following is
Mass of a photon of frequency v is given by
In the nuclear reaction $ _{13}A{{l}^{27}}(d,\alpha )x,X $ is:
The resistance of a discharge tube is
A disc is rolling (without slipping) on a horizontal surface. C is its centre and Q and P are two points equidistant from C. Let $v_P$, $v_q$ and $v_c$ be the magnitude of velocities of points P,Q and C respectively, then
The internal resistance of a cell of e.m.f. 2 V is $0.1\, \Omega$ It is connected to a resistance of $3.9\, \Omega$. The voltage across the cell will be
A potentiometer consists of a wire of length 4 m and resistance $10\, \Omega$ It is connected to a cell of e.m.f. 2 V. The potential difference per unit length of the wire will be
In a meter bridge, the balancing length from the left end (standard resistance of one ohm is in the right gap) is found to be 20 cm. The value of the unknown resistance is
A person aiming to reach exactly opposite point on the bank of a stream is swimming with a speed of 0.5 m/s at an angle of $ 120^\circ$ with the direction of flow of water. The speed of water in the stream, is
A mass m supported by a massless string wound around a uniform hollow cylinder of mass m and radius R. If the string does not slip on the cylinder, with what acceleration will the mass fall on release?
The average kinetic energy of a gas molecules at $27^{\circ} C$ is $6.21 \times 10^{-21} J$. Its average kinetic energy at $227^{\circ}C$ will be
A body is projected vertically upwards from the surface of a planet of radius $R$ with a velocity equal to half the escape velocity for that planet. The maximum height attained by the body is
A mirror forms a real image of unit magnification, Its nature is
Electric charges $+ 10\mu C, + 5\mu C, - 3 \mu C\, and\, + 8 \mu C$ are placed at the comers of a square of side $\sqrt2\,m$. The potential at the centre of the square (V) is
Magnetic field intensity at the centre of coil of 50 turns, radius 0.5 m and carrying a current of 2 A, is
Mean life of a radioactive element is one year. Then its half life is (in year)
Biaxial crystal among the following is
The number of atoms in a radioactive sample reduces from 1000 to 100 in two days. Then the number of atoms remaining at the end of four days is
Ionisation energy of hydrogen atom is 13.6 eV. Then the energy required to ionise a hydrogen atom in which the electron is in the second orbit from the nucleus is (eV)
A convex lens of refractive index $n$ behaves as a convex lens of smaller power in a liquid of refractive index $n_1$ and as a concave lens in another liquid of refractive index $n_2$. Then relation between $n,n_1$ and $n_2$ is
Three similar cells, each of emf 2 V and internal resistance $r\,\Omega$ send the same current through an external resistance of $2\,\Omega$ when connected in series or in parallel. The strength of the current flowing through the external resistance is (A)
S.l. unit of surface tension is
Interference fringes are obtained using two coherent sources whose intensities are in the ratio 4 : 1. Then the ratio of the intensities of the bright and dark bands is