List of top Physics Questions asked in CBSE CLASS XII

Two wires P and Q are made of the same material. Wire Q has twice the diameter and half the length of wire P. If the resistance of wire P is \( R \), the resistance of wire Q will be:
The resistance of a wire of length \( L \) and radius \( r \) is \( R \). Which one of the following would provide a wire of the same material with resistance \( \frac{R}{2} \)?
The figure shows the voltage (V) versus the current (I) graphs for a wire at two temperatures \( T_1 \) and \( T_2 \). One can conclude that:
voltage (V) versus the current (I) graphs
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.
Three batteries E1, E2, and E3 of emfs and internal resistances
Calculate the value of the current passing through the battery in the given circuit diagram.
Derive an expression for the torque acting on a rectangular current loop suspended in a uniform magnetic field.
A capacitor is charged by a battery to a potential difference \( V \). It is disconnected from the battery and connected across another identical uncharged capacitor. Calculate the ratio of total energy stored in the combination to the initial energy stored in the capacitor.
“There is a limit to the amount of charge that can be stored on a given capacitor.” Explain.
In a Young’s double-slit experiment, two light waves, each of intensity \( I_0 \), interfere at a point, having a path difference \( \frac{\lambda}{8} \) on the screen. Find the intensity at this point.
Light consisting of two wavelengths 600 nm and 480 nm is used to obtain interference fringes in a double slit experiment. The screen is placed 1.0 m away from slits which are 1.0 mm apart. (i) Calculate the distance of the third bright fringe on the screen from the central maximum for wavelength 600 nm.
The ends of six wires, each of resistance R (= 10 \(\Omega\)) are joined as shown in the figure. The points A and B of the arrangement are connected in a circuit. Find the value of the effective resistance offered by it to the circuit.
The ends of six wires, each of resistance
You are provided with a large number of 1 \(\mu\text{F}\) identical capacitors and a power supply of 1200 V. The dielectric medium used in each capacitor can withstand up to 200 V only. Find the minimum number of capacitors and their arrangement required to build a capacitor system of equivalent capacitance of 2 \(\mu\text{F}\) for use with this supply.
A parallel plate capacitor with plate area \( A \) and plate separation \( d \) has a capacitance \( C_0 \). A slab of dielectric constant \( K \) having area \( A \) and thickness \( \left(\frac{d}{4}\right) \) is inserted in the capacitor, parallel to the plates. Find the new value of its capacitance.
An electric dipole of dipole moment \( 1.0 \times 10^{-12} \ \text{Cm} \) lies along the x-axis. An electric field of magnitude \( 2.0 \times 10^4 \ \text{NC}^{-1} \) is switched on at an instant in the region. The unit vector along the electric field is \( \frac{\sqrt{3}}{2} \hat{i} + \frac{1}{2} \hat{j} \). The magnitude of the torque acting on the dipole at that instant is:
Explain the transmission of optical signal through an optical fiber with a diagram.
Answer the following giving reason:
(a) All the photoelectrons do not eject with the same kinetic energy when monochromatic light is incident on a metal surface.
(b) The saturation current in case (a) is different for different intensity.
(c) If one goes on increasing the wavelength of light incident on a metal sur face, keeping its intensity constant, emission of photoelectrons stops at a certain wavelength for this metal.
Explain the process of formation of 'depletion layer' and 'potential barrier' in a p-n junction region of a diode, with the help of a suitable diagram. Which feature of junction diode makes it suitable for its use as a rectifier?
You are required to design an air-filled solenoid of inductance 0.016 H having a length 0.81 m and radius 0.02 m. The number of turns in the solenoid should be:
A metal rod of length 50 cm is held vertically and moved with a velocity in a magnetic field at the place of 0.4 G. The emf induced across the ends of the rod is:
Define 'Mass defect' and 'Binding energy' of a nucleus. Describe the 'Fission process' on the basis of binding energy per nucleon.
The given diagram exhibits the relationship between the wavelength of the electromagnetic waves and the energy of photons associated with them. The three points P, Q, and R marked on the diagram may correspond respectively to:
relationship between the wavelength of the electromagnetic waves

A battery of emf \( E \) and internal resistance \( r \) is connected to a rheostat. When a current of 2A is drawn from the battery, the potential difference across the rheostat is 5V. The potential difference becomes 4V when a current of 4A is drawn from the battery. Calculate the value of \( E \) and \( r \).

Assertion (A): The deflection in a galvanometer is directly proportional to the current passing through it. 

Reason (R): The coil of a galvanometer is suspended in a uniform radial magnetic field.

Out of the four options given, in which transition will the emitted photon have the maximum wavelength?
Differentiate between magnetic flux through an area and magnetic field at a point.