List of top Physics Questions asked in UP Board XII

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'.
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.
State Huygens' principle of secondary wavelets. With the help of this principle, explain the laws of reflection of light.
Explain the working method of p-n junction diode in reverse bias with the help of a circuit diagram.
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.
Explain the meaning of binding energy of a nucleus. Write the dependency of binding energy per nucleon on the mass number of the nucleus.
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.
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 an astronomical telescope? Draw ray diagram for an astronomical telescope when final image is formed at infinity.
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.
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.
On which principle does a nuclear reactor work?
Do two equipotential surfaces intersect each other? Answer with reason.
What is the meaning of electrical capacity of a conductor? Find the unit of the electrical capacity of the conductor.
Equation of electric field of a plane electromagnetic wave is given as:
\[ E_z = 60 \sin(500x + 1.5 \times 10^{11} t) \, \text{V/m}. \] Write the equation for the magnetic field of the wave.
On connecting a cell of e.m.f. 0.5 volt with an external resistance of 1.9 $\Omega$, the current flowing is 0.75 A. The internal resistance of the cell is:
In an alternating circuit, the reading of the voltmeter is 220 V. Write the peak value of the voltage.
Write down Einstein's equation for the photoelectric effect.
Write de-Broglie formula for the wavelength of matter waves.
Electrostatic force between two point charges placed in a medium of dielectric constant \( k \) is \( F_1 \). On changing the medium, electrostatic force between the charges becomes \( F_2 \). Dielectric constant of the medium will be:
A concave lens of focal length -18 cm is placed in contact with a convex lens of focal length +12 cm. The focal length of the combination will be:
A charge \( q \) enters with speed \( v \) in the direction of magnetic field \( B \). The force on the charge in magnetic field will be:
Resistivity of a conducting wire depends on: