List of top Physics Questions asked in CBSE CLASS XII

Draw a ray diagram for the formation of the image of an object by a convex mirror. Hence, obtain the mirror equation.
Differentiate between a wavefront and a ray.
A dielectric slab of dielectric constant K K and thickness t t is inserted between plates of a parallel plate capacitor of plate separation d d and plate area A A . Obtain an expression for its capacitance.
Using Gauss's law, show that the electric field E E at a point due to a uniformly charged infinite plane sheet is given by E=σ2ϵ0 E = \frac{\sigma}{2\epsilon_0} , where symbols have their usual meanings.
Mention the factors on which the resonant frequency of a series LCR circuit depends. Plot a graph showing variation of impedance of a series LCR circuit with the frequency of the applied AC source.
With the help of a diagram, briefly explain the construction and working of an AC generator.
The focal length of an equiconvex lens:
A beam of light coming parallel to the principal axis of a convex lens L1 L_1 of focal length 16 cm is incident on it. Another convex lens L2 L_2 of focal length 12 cm is placed coaxially at a distance 40 cm from L1 L_1 . The nature and distance of the final image from L2 L_2 will be:
During the formation of a p-n junction:
At a given temperature, the number of intrinsic charge carriers in a semiconductor is 2.0×1010 2.0 \times 10^{10} cm−3^{-3}. It is doped with pentavalent impurity atoms. As a result, the number of holes in it becomes 8×103 8 \times 10^3 cm−3^{-3}. The number of electrons in the semiconductor is:
Initially, during the formation of a p-n junction:
When Ge is doped with a pentavalent impurity, the energy required to free the weakly bound electron from the dopant is about:
In normal adjustment, for a refracting telescope, the distance between the objective and eyepiece lens is 1.00 m. If the magnifying power of the telescope is 19, find the focal length of the objective and the eyepiece lens.
Two electric heaters have power ratings P1 P_1 and P2 P_2 , at voltage V V . They are connected in series to a DC source of voltage V V . Find the power consumed by the combination. Will they consume the same power if connected in parallel across the same source?
Assertion (A): In interference and diffraction of light, light energy reduces in one region producing a dark fringe. It increases in another region and produces a bright fringe.
Reason (R): This happens because energy is not conserved in the phenomena of interference and diffraction.
A proton and an α \alpha -particle are accelerated through different potentials V1 V_1 and V2 V_2 respectively so that they have the same de Broglie wavelengths. Find V1V2 \frac{V_1}{V_2} .
A ray of light is incident normally on one face of an equilateral glass prism of refractive index P P . When the prism is completely immersed in a transparent medium, it is observed that the emergent ray just grazes the adjacent face. Find the refractive index of the medium.
Assertion (A): The temperature coefficient of resistance is positive for metals and negative for p-type semiconductors.
Reason (R): The charge carriers in metals are negatively charged, whereas the majority charge carriers in p-type semiconductors are positively charged.
Assertion (A): Electrons are ejected from the surface of zinc when it is irradiated by yellow light.
Reason (R): Energy associated with a photon of yellow light is more than the work function of zinc.
Assertion (A): When electrons drift in a conductor, it does not mean that all free electrons in the conductor are moving in the same direction.
Reason (R): The drift velocity is superposed over large random velocities of electrons.
In the Balmer series of the hydrogen atom, as the wavelength of spectral lines decreases, they appear:
The phase difference between electric field E⃗ \vec{E} and magnetic field B⃗ \vec{B} in an electromagnetic wave propagating along the z-axis is:
The magnetic susceptibility for a diamagnetic material is:
A straight wire is kept horizontally along the east-west direction. If a steady current flows in the wire from east to west, the magnetic field at a point above the wire will point towards:
A galvanometer of resistance 100 Ω \Omega is converted into an ammeter of range (0 – 1 A) using a resistance of 0.1 Ω \Omega . The ammeter will show full-scale deflection for a current of about: