List of top Physics Questions asked in CBSE CLASS XII

Which of the following is an electrical conductor at room temperature?

An ammeter connected in series in an AC circuit reads \( 10 \, \text{A} \). The maximum value of current at any instant in the circuit is:

The magnification produced by a spherical mirror is \( -2.0 \). The mirror used and the nature of the image formed will be:

A bar magnet is initially at right angles to a uniform magnetic field. The magnet is rotated till the torque acting on it becomes one-half of its initial value. The angle through which the bar magnet is rotated is:

A particle having charge \( +q \) enters a uniform magnetic field \( \vec{B} \) as shown in the figure. The particle will describe:

A current flows through a cylindrical conductor of radius \( R \). The current density at a point in the conductor is \( j = \alpha r \) (along its axis), where \( \alpha \) is a constant and \( r \) is the distance from the axis of the conductor. The current flowing through the portion of the conductor from \( r = 0 \) to \( r = \frac{R}{2} \) is proportional to:

The amplitude of electric field in an electromagnetic wave in free space is \( 1000 \, \text{Vm}^{-1} \). The amplitude of the magnetic field in this electromagnetic wave is:

A body acquires charge \( 8.0 \times 10^{-12} \, \text{C} \). The mass of the body:

In the circuit, three ideal cells of e.m.f. \( V \), \( V \), and \( 2V \) are connected to a resistor of resistance \( R \), a capacitor of capacitance \( C \), and another resistor of resistance \( 2R \) as shown in the figure. In the steady state, find (i) the potential difference between P and Q, (ii) the potential difference across capacitor C.

Two wires of the same material and the same radius have their lengths in the ratio 2:3. They are connected in parallel to a battery which supplies a current of 15 A. Find the current through the wires.

A transparent solid cylindrical rod (refractive index \( \frac{2}{\sqrt{3}} \)) is kept in air. A ray of light incident on its face travels along the surface of the rod, as shown in the figure. Calculate the angle \( \theta \).

Two coherent light waves, each having amplitude ‘a’, superpose to produce an interference pattern on a screen. The intensity of light as seen on the screen varies between:

Which of the following electromagnetic waves has photons of largest momentum?

Which of the following rays coming from the Sun plays an important role in maintaining the Earth’s warmth?

The magnetic flux linked with a coil changes with time \( t \) as \( \phi = (8t^2 + 5t + 7) \), where \( t \) is in seconds and \( \phi \) is in Wb. The value of emf induced in the coil at \( t = 4 \) s is:

The electric field at a point in a region is given by \( \vec{E} = \alpha \frac{\hat{r}}{r^3} \), where \( \alpha \) is a constant and \( r \) is the distance of the point from the origin. The magnitude of potential of the point is:

A charged particle gains a speed of \(10^6 \, \text{ms}^{-1}\) when accelerated from rest through a potential difference of 10 kV. It enters a region of magnetic field of 0.4 T such that \( \vec{v} \perp \vec{B} \). The radius of the circular path described by it is:

Three batteries E1, E2, and E3 of emfs and internal resistances (4 V, 2 \(\Omega\)), (2 V, 4 \(\Omega\)) and (6 V, 2 \(\Omega\)) respectively are connected as shown in the figure. Find the values of the currents passing through batteries E1, E2, and E3.

Current I (= 1 A) is passing through a copper rod (n = \(8.5 \times 10^{28} \, \text{m}^{-3}\)) of varying cross-sections as shown in the figure. The areas of cross-section at points A and B along its length are \(1.0 \times 10^{-7} \, \text{m}^2\) and \(2.0 \times 10^{-7} \, \text{m}^2\) respectively. Calculate:

(I) the ratio of electric fields at points A and B.
(II) the drift velocity of free electrons at point B.

Define self-inductance of a coil. Derive the expression for the energy required to build up a current \(I\) in a coil of self-inductance \(L\).