List of top Questions asked in UP Board XII

What is Brewster's law?
Write down the unit of magnetic dipole moment.
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?
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).
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?
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 minority charge carriers in n type of semiconductors:
The length of the image formed by a concave mirror:
Explain the working method of p-n junction diode in reverse bias with the help of a circuit diagram.
In A.C. circuits, what is the difference between impedance and resistance? Write the formula for power factor in L-C-R circuit.
Which nature of light is supported by Young’s double slit experiment? The light used in Young’s double slit experiment contains two wavelengths, 6000 \AA\ and 5000 \AA. Separation between the slits is \(10^{-3}\) m and the screen is at a distance of 1 m from the slits. Find minimum distance from the central maxima where bright fringes for both the wavelengths are coincident.
What is the photoelectric effect? Which nature of light is shown by it? Threshold frequency of a metal is \(2.3 \times 10^{14}\) Hz. If the frequency of incident light is \(8.2 \times 10^{14}\) Hz, what will be the stopping potential? Calculate work function of the metal also.
Derive the formula for the capacitance of a parallel plate capacitor partially filled with a dielectric medium between the plates.
What is meant by magnetic effect of electric current? Find the expression for the force acting between two parallel current-carrying conducting wires. On this basis, define the unit of electric current 'ampere'.
State Huygens' principle of secondary wavelets. With the help of this principle, explain the laws of reflection of light.
Write down the equation for Lorentz force. An electron passes undeviated from a place where an electric field \(5 \times 10^4~\text{V/m}\) and magnetic field of \(5 \times 10^{-2}~\text{weber/m}^2\) are applied. Calculate the velocity of the electron.
Explain the meaning of binding energy of a nucleus. Write the dependency of binding energy per nucleon on the mass number of the nucleus.
Give pictorial representation of polarized and unpolarised light. Polarizing angle for a transparent medium is 60°. Find the value of angle of refraction and refractive index of the medium.
Name the waves of longest wavelength and highest frequency in the given electromagnetic waves — microwaves, X-rays, radio waves, and \(\gamma\)-rays. What is meant by displacement current?
What is the meaning of stationary orbit of atom? Deriving formula for the energy of the electron in the stationary orbit of the hydrogen atom, mention its relation with the radius of the orbit of electron.
What is an astronomical telescope? Draw ray diagram for an astronomical telescope when final image is formed at infinity.
State Gauss's law in electrostatics. On the basis of it, obtain the formula for the electric field produced due to a plane charged plate.
Do two equipotential surfaces intersect each other? Answer with reason.
On which principle does a nuclear reactor work?
What is the meaning of electrical capacity of a conductor? Find the unit of the electrical capacity of the conductor.