List of top Physics Questions asked in CBSE CLASS XII

Two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer from the options below:

(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(C) Assertion (A) is true, but Reason (R) is false.
(D) Both Assertion (A) and Reason (R) are false.

Assertion (A): Electrostatic force is a conservative force.

Reason (R): In an electrostatic field, the work done between two points per unit positive charge depends on the path followed.

Which of the following assumptions has been used to obtain the relation \(\dfrac{v_s}{v_p} = \dfrac{N_s}{N_p}\) for a transformer?

Whenever a magnet is moved either towards or away from a conducting coil, an emf is induced whose magnitude is independent of the:

A charge \(Q\) is enclosed by a spherical Gaussian surface of radius \(R\). If the radius is doubled, then the total electric flux through the surface:

The figure shows the variation of maximum kinetic energy (\(K_{max}\)) of emitted electrons as a function of the frequency \(\nu\) of radiation incident on a photosensitive surface. The slope of the curve is:

A small metallic sphere S of charge \(+q\) is placed exactly at a point midway between two point charges A \((+Q)\) and B \((+Q)\) where \(Q \gg q\). If the sphere is slightly displaced towards charge A and released, then:

The potential energy of a pair of nucleons is minimum when they are separated by about:

Draw circuit arrangement for studying V-I characteristics of a p-n junction diode.
A right-angled isosceles glass prism ABC is kept in contact with an equilateral triangular prism DBC as shown in the figure. Both prisms are made of the same glass of refractive index 1.6. Trace the path of the ray MN incident normally on face AB as it passes through the combination.
right-angled isosceles glass prism
(a) Differentiate between 'conduction current' and 'displacement current', giving one similarity and one dissimilarity between them.
(b) Explain the existence of electromagnetic waves in free space, using the concept of displacement current.
In a circular loop of radius \( R \), current \( I \) enters at point \( A \) and exits at point \( B \), as shown in the figure. The value of the magnetic field at the centre \( O \) of the loop is:
A compound microscope has an objective and an eyepiece of focal lengths \( f_0 \) and \( f_e \), respectively. To obtain a large magnification of a small object, the microscope should have:
The work function of a material is 2.21 eV. Which of the following cannot produce photoelectrons from it?
Consider two identical dipoles \( D_1 \) and \( D_2 \). Charges \( -q \) and \( q \) of dipole \( D_1 \) are located at \( (0, 0) \) and \( (a, 0) \) and that of dipole \( D_2 \) at \( (0, a) \) and \( (0, 2a) \) in \( x \)-\( y \) plane, respectively. The net dipole moment of the system is
A right-angled prism \( ABC \) (refractive index \( \sqrt{2} \)) is kept on a plane mirror as shown in the figure. A ray of light is incident normally on the face \( AC \). Find the angle of deviation produced by the prism.

(i) State Lenz's law and explain how this law is a consequence of conservation of energy principle.

(ii) A square shaped loop of side \(\dfrac{\ell}{2}\) is initially lying outside a region of uniform magnetic field \(\vec{B}\) as shown in the figure. The loop is moved towards right with a constant velocity \(\vec{v}\) till it goes out of the region of magnetic field.

(I) What will be the directions of induced current when the loop enters the field and when it leaves the field ?

(II) Draw the plots showing the variation of magnetic flux \(\phi\) linked with the loop with time \(t\) and variation of induced emf \(E\) with time \(t\). Mark the relevant values of \(E\), \(\phi\) and \(t\) on the graphs.


Which pair of readings of ideal voltmeter and ideal ammeter in the given circuit is possible when a suitable power source of 3 \( \Omega \) internal resistance is connected between P and Q ?
The number of turns between different pairs of output terminals are shown for a step-up transformer. Input voltage of 20 V is applied between A and B. Between which two terminals will the output be 120 V ?
A soft iron rod X is allowed to fall on the two poles of a U shaped permanent magnet as shown in figure. A coil is wrapped over one arm of the U shaped magnet. During fall of the rod, the current in the coil will be

The minimum energy required to free the electron from the ground state of the hydrogen atom is :

An ac source of voltage \( V = V_0 \sin \omega t \) is connected to a circuit element \( X \). It is observed that the current flowing through \( X \) varies as \( I = I_0 \sin\left(\omega t - \dfrac{\pi}{2}\right) \).
(c) Draw plots showing the variation of voltage and current with time over one cycle of applied ac.
An ac source of voltage \( V = V_0 \sin \omega t \) is connected to a circuit element \( X \). It is observed that the current flowing through \( X \) varies as \( I = I_0 \sin\left(\omega t - \dfrac{\pi}{2}\right) \).
(b) Plot a graph to show the variation of reactance of the element with the frequency of the applied voltage.
Draw a graph of potential energy between a pair of nucleons as a function of their separation.

Find the \(Q\) value of the following nuclear reaction:

\({}_6^{12}\text{C} + {}_6^{12}\text{C} \longrightarrow {}_{10}^{20}\text{Ne} + {}_2^{4}\text{He}\)

Is this reaction exothermic or endothermic ?

Given: \(m({}_6^{12}\text{C}) = 12.000000\ \text{u}\), \(m({}_{10}^{20}\text{Ne}) = 19.992439\ \text{u}\), \(m({}_2^{4}\text{He}) = 4.002603\ \text{u}\), \(1\ \text{u} = 931\ \text{MeV}/c^2\)

The magnetic moment (\(5\;\text{J/T}\)) of a bar magnet points along a uniform magnetic field \(0.4\;\text{T}\).

(a) Calculate (i) the potential energy of the bar magnet, and (ii) the work done in turning the magnet by \(180^{\circ}\).

(b) In which case is the potential energy of the magnet minimum ?