List of top Physics Questions asked in CBSE CLASS XII

Assertion (A): Two long parallel wires, freely suspended and connected in series to a battery, move apart.
Reason (R):Two wires carrying current in opposite directions repel each other.
Assertion (A): The mutual inductance between two coils is maximum when the coils are wound on each other.
Reason (R): The flux linkage between two coils is maximum when they are wound on each other.
Two beams, A and B whose photon energies are $3.3 \, \text{eV$ and $11.3 \, \text{eV}$ respectively, illuminate a metallic surface (work function $2.3 \, \text{eV}$) successively. The ratio of maximum speed of electrons emitted due to beam A to that due to beam B is:}
The waves associated with a moving electron and a moving proton have the same wavelength $\lambda$. It implies that they have the same:
Assertion (A): In photoelectric effect, the kinetic energy of the emitted photoelectrons increases with increase in the intensity of the incident light.
Reason (R): Photoelectric current depends on the wavelength of the incident light.
Ge is doped with As. Due to doping:}
The transition of electron that gives rise to the formation of the second spectral line of the Balmer series in the spectrum of hydrogen atom corresponds to:
In the four regions, I, II, III, and IV, the electric fields are described as: Region I: $E_x = E_0 \sin(kz - \omega t)$
Region II: $E_x = E_0$
Region III: $E_x = E_0 \sin kz$
Region IV: $E_x = E_0 \cos kz$
The displacement current will exist in the region:
The reactance of a capacitor of capacitance $C$ connected to an AC source of frequency $\omega$ is $X$. If the capacitance of the capacitor is doubled and the frequency of the source is tripled, the reactance will become:
A galvanometer of resistance $G \, \Omega$ is converted into an ammeter of range 0 to 1 A. If the current through the galvanometer is 0.1\% of 1 A, the resistance of the ammeter is:
A loop carrying a current $I$ clockwise is placed in $x-y$ plane, in a uniform magnetic field directed along $z$-axis. The tendency of the loop will be to:
A $10 \, \text{cm$ long wire lies along $y$-axis. It carries a current of $1.0 \, \text{A}$ in positive $y$-direction. A magnetic field $\vec{B} = (5 \, \text{mT}) \, \hat{j} - (8 \, \text{mT}) \, \hat{k}$ exists in the region. The force on the wire is:}
Ten capacitors, each of capacitance 1 \(\mu\)F, are connected in parallel to a source of 100 V. The total energy stored in the system is equal to:
Consider the circuit shown in the figure. The potential difference between points A and B is: \includegraphics[width=0.4\linewidth]{872image.png}
A thin plastic rod is bent into a circular ring of radius R. It is uniformly charged with charge density $\lambda$. The magnitude of the electric field at its centre is:
The Coulomb force (\( F \)) versus \( \frac{1}{r^2} \) graphs for two pairs of point charges (\( q_1 \) and \( q_2 \)) and (\( q_2 \) and \( q_3 \)) are shown in the figure. The charge \( q_2 \) is positive and has the least magnitude. Then: 
The Coulomb force ( F F) versus 1 r 2
A thin spherical conducting shell of radius \( R \) has a charge \( q \). A point charge \( Q \) is placed at the center of the shell. Find:
(i) The charge density on the outer surface of the shell.
(ii) The potential at a distance \( R/2 \) from the center of the shell.
Two long insulated straight wires carrying currents of \( 3A \) and \( 5A \) are arranged in the XY plane as shown in the figure. Find the magnitude and direction of the net magnetic fields at points \( P_1(2m, 2m) \) and \( P_2(-1m, 1m) \). 
Two long insulated straight wires carrying currents
What is meant by displacement current? How is this current different from the conduction current? A capacitor is being charged by a source of emf. Justify the continuity of current in the circuit.
Find the temperature at which the resistance of a conductor increases by 25% of its value at \( 27^\circ \text{C} \). The temperature coefficient of resistance of the conductor is \( 2.0 \times 10^{-4} \, \text{C}^{-1} \).
In the given network, calculate: 
(i) Effective resistance between points A and M, and 
(ii) Power supplied by the battery. 
Effective resistance between
An infinite straight conductor is kept along \( X'X \) axis and carries a current \( I \). A charge \( q \) at point \( P(0, r) \) starts moving with velocity \( \vec{v} = v_0 \, \hat{j} \) as shown in figure. Find the direction and magnitude of force initially experienced by the charge. 
An infinite straight conductor
Explain the following giving reasons:
(i) Electromagnetic waves differ considerably in their mode of interaction with matter.
(ii) Food items to be heated in microwave ovens must contain water.
(iii) Welders wear face mask with glasses during welding.
An infinitely long straight wire having a charge density \( \lambda \) is kept along the y-axis in the x-y plane. The Coulomb force on a point charge \( q \) at a point \( P(x, 0) \) will be:
Two conducting spherical shells A and B of radii \( R \) and \( 2R \) are kept far apart and charged to the same charge density \( \sigma \). They are connected by a wire. Obtain an expression for the final potential of shell A.