List of top Physics Questions asked in CBSE CLASS XII

A 2.0 cm segment of wire, carrying 5.0 A current in positive y-direction lies along the y-axis, as shown in the figure. The magnetic field at a point (3 m, 4 m, 0) due to this segment (part of a circuit) is:
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A circular loop of wire, carrying a current 'I' is lying in the xy-plane with its centre coinciding with the origin. It is subjected to a uniform magnetic field pointing along the +z-axis. The loop will:
A current carrying circular loop of magnetic moment \( \vec{M} \) is suspended in a vertical plane in an external magnetic field \( \vec{B} \) such that its plane is normal to \( \vec{B} \). The work done in rotating this loop by 45° about an axis perpendicular to \( \vec{B} \) is closest to:
A proton is taken from point P1 to point P2, both located in an electric field. The potentials at points P1 and P2 are -5 V and +5 V respectively. Assuming that kinetic energies of the proton at points P1 and P2 are zero, the work done on the proton is:
Consider a group of charges \( q_1, q_2, q_3, \ldots \) such that \( \sum q \neq 0 \). Then equipotentials at a large distance, due to this group are approximately:
Consider a neutron (mass $m$) of kinetic energy $E$ and a photon of the same energy. Let $\lambda_n$ and $\lambda_p$ be the de Broglie wavelength of the neutron and the wavelength of the photon, respectively. Obtain an expression for $\frac{\lambda_n{\lambda_p}$.}
Which of the following quantity/quantities remains same in primary and secondary coils of an ideal transformer? Current, Voltage, Power, Magnetic flux
A circular coil of radius 10 cm is placed in a magnetic field \( \vec{B} = (1.0 \hat{i} + 0.5 \hat{j}) \, \text{mT} \) such that the outward unit vector normal to the surface of the coil is \( (0.6 \hat{i} + 0.8 \hat{j}) \). The magnetic flux linked with the coil is:
Define resistivity of a conductor. How does the resistivity of a conductor depend upon the following:
de Broglie wavelength \( \lambda \) as a function of \( \frac{1}{\sqrt{K}} \), for two particles of masses \( m_1 \) and \( m_2 \), is shown in the figure. Here, \( K \) is the energy of the moving particles. (a) What does the slope of a line represent? 
(b) Which of the two particles is heavier? 
(c) Is this graph also valid for a photon? Justify your answer in each case.

 
The interface AB between the two media A and B is shown in the figure. In the denser medium A, the incident ray PQ makes an angle of \( 30^\circ \) with the horizontal. The refracted ray is parallel to the interface. The refractive index of medium B with respect to medium A is:
Two media A and B are separated by a plane boundary. The speed of light in medium A and B is \( 2 \times 10^8 \, \text{ms}^{-1} \) and \( 2.5 \times 10^8 \, \text{ms}^{-1} \), respectively. The critical angle for a ray of light going from medium A to medium B is:
Two long straight wires 1 and 2 are kept as shown in the figure. The linear charge density of the two wires are \(\lambda\) 1 = 10 C/m and \(\lambda\)2 = -20 C/m. Find the net force F experienced by an electron held at point P:
A particle of mass \( m \) and charge \( q \) is moving with a velocity \( \vec{v} \) in a magnetic field \( \vec{B} \) as shown in the figure. Show that it follows a helical path. Hence, obtain its frequency of revolution.
charged particle in a magnetic field
 
Draw a labelled ray diagram of a compound microscope showing image formation at least distance of distinct vision. Derive an expression for its magnifying power.
In Young's double-slit experiment using monochromatic light of wavelength \( \lambda \), the intensity of light at a point on the screen, where path difference is \( \lambda \), is \( K \) units. Find the intensity of light at a point on the screen where the path difference is \( \lambda / 6 \).
A telescope consists of two lenses of focal length 100 cm and 5 cm. Find the magnifying power when the final image is formed at infinity.
What is current sensitivity of a galvanometer? Show how the current sensitivity of a galvanometer may be increased. Increasing the current sensitivity of a galvanometer may not necessarily increase its voltage sensitivity. Explain.
A moving coil galvanometer has a resistance of 15 Ω and takes 20 mA to produce full-scale deflection. How can this galvanometer be converted into a voltmeter of range 0 to 100 V?
Three point charges \( q \), \( 2q \) and \( nq \) are placed at the vertices of an equilateral triangle. If the potential energy of the system is zero, find the value of \( n \).
State Gauss's law in electrostatics. Apply this to obtain the electric field E at a point near a uniformly charged infinite plane sheet:
Draw an intensity distribution graph in case of a double-slit interference pattern.
Give any two differences between the interference pattern obtained in Young's double-slit experiment and a diffraction pattern due to a single slit.
In a hydrogen atom, the electron moves in an orbit of radius \( 2 \, \text{Å} \) making \( 8 \times 10^{14} \) revolutions per second. Find the magnetic moment associated with the orbital motion of the electron.
Potential difference across a cell in the open circuit is 6 V. It becomes 4 V when a current of 2 A is drawn from it. The internal resistance of the cell is: