List of top Physics Questions asked in UP Board XII

What is the principle of a moving coil galvanometer? Draw its neat labelled diagram. How is the sensitivity of the galvanometer increased?
What is meant by displacement current? The amplitude of electric field of an electromagnetic wave is \( E_0 = 120 \, \text{N/C} \) and frequency is \( \nu = 50 \, \text{MHz} \). Find out:
i) Amplitude of the magnetic field \( B_0 \) ii) Wavelength \( \lambda \) of the electromagnetic wave.
The area of a plane coil 1000 turns is 500 cm\(^2\) and it is held perpendicular to a uniform magnetic field of \(4 \times 10^{-4}\) weber/m\(^2\). It is turned through 180° angle in 0.1 second. Calculate the average induced e.m.f. produced in the coil.
In the given figure, LCR circuit is shown. Voltage of the alternating current source is \( V = 100 \sin (500 t) \) volt. Calculate for the circuit:
What is meant by resonant circuit? Write down the required condition for the L-C-R series resonant circuit and expression for the frequency in resonant condition.
Hydrogen atom in its ground energy state absorbs a photon, which excites it to an energy level of \(n = 4\). Calculate the frequency of photon.
What is meant by the wattless current?
The binding energy per nucleon of \(\alpha\)-particle (\(_2^4\text{He}\)) is 7 MeV. What is its total binding energy?
Obtain the formula for the intensity of electric field outside a charged thin spherical shell with the help of Gauss' law.
Enunciate the difference between the conductors and semiconductors on the basis of energy bands in solids.
The stopping potential for the photoelectric current is obtained as 4 V for a metal surface by a monochromatic light of wavelength \( \lambda \), incident on it. The stopping potential becomes \(V\) for the incident light of wavelength \( 2\lambda \) on this surface. Find the formula of threshold wavelength \( \lambda_0 \) in terms of \( \lambda \).
Write down any two uses of microwaves.
Write down the unit of magnetic dipole moment.
The unit of coefficient of self-inductance is:
Following charged particles are projected perpendicular in a uniform magnetic field with the same velocity. The maximum force is exerted on:
n electric dipoles are placed inside a closed surface. Total electric flux linked with the closed surface will be:
A \( 4 \, \Omega \) resistance wire is bent into a shape of a circle. What will be the effective resistance between the ends of its diameter?
Electrons and protons are accelerated by the same potential difference. The ratio of their de Broglie wavelengths is:
What is Brewster's law?
Write down the formula for refraction of light from a spherical surface and with the help of this, derive the relation \( \frac{1}{f} = (n - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right) \) for a thin lens. Also show that, the focal length for concave lens will be negative.
The length of the image formed by a concave mirror:
The minority charge carriers in n type of semiconductors:
Explain the difference between self-inductance and mutual inductance. Define the coefficient of self-inductance and coefficient of mutual inductance. A plane coil of area 100 cm$^2$ is rotating in a magnetic field of 2 weber/m$^2$ with angular velocity 20 rad/s. What will be the maximum induced electromotive force in the coil?
Mention the most important conclusion of Rutherford's alpha-particle scattering experiment. Define isotopic, isobaric, and isotonic nuclei. Find the energy equivalent to one atomic mass unit in joules and MeV (1 u = 1.6605 × \(10^{-27}\) kg).
State Huygens' principle of secondary wavelets. With the help of this principle, explain the laws of reflection of light.