List of top Physics Questions asked in UP Board XII

A proton and an \( \alpha \)-particle are accelerated by the same potential difference. Find out the ratio of their de Broglie wavelengths.
What is Ampere's circuital law? Using it, obtain the formula for the magnetic field produced due to a straight current-carrying conductor of infinite length.
If the circumference of the nth orbit of an electron is \(S\) and the corresponding de Broglie wavelength of the orbit is \(\lambda\), then on the basis of Bohr's atom model, prove that \(S = n\lambda\).
What is meant by doping in semiconductors?
Mention any two applications of total internal reflection.
How is a galvanometer converted into a voltmeter?
What is the meaning of stopping potential in photoelectric effect?
What is meant by wattless current?
In hydrogen atom, the kinetic energy of electron in an orbit of radius \( r \), is given by:
Draw a labelled ray diagram of an astronomical telescope and derive the formula of its magnifying power.
1 GHz frequency corresponds to which region of the electromagnetic spectrum?
If polarising angle is \( \theta_1 \), and critical angle is \( \theta_2 \), then:
An air bi-convex lens of 10 cm radius of curvature is placed in a cylinder of glass (\(n = \frac{3}{2}\)), as shown in the figure. Find the focal length and nature of the lens. If a liquid of refractive index \(n' = 2\) is filled in the lens, then what will be the power and nature of the lens?
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The magnetic susceptibility \( \chi \) of paramagnetic substance varies with absolute temperature \( T \) as:
The correct relationship of mobility \( \mu \) of charge carrier with drift velocity \( v_d \) and electric field \( E \), is:
Draw energy level diagram for hydrogen atom. Show the transitions of the first line of Lyman series and second line of Balmer series. Find out the ratio of their wavelengths.
The voltage and current of an ac circuit are represented as \( V = 100 \sin(100t) \) volt and \( i = 100 \sin(100t + \frac{\pi}{3}) \) mA respectively. The power dissipated in the circuit is:
Derive the formula for the capacitance of a parallel plate capacitor, when a dielectric slab is partially filled in between its plates.
Two cells are of emf's \(E_1\) and \(E_2\) and their internal resistances are \(r_1\) and \(r_2\) respectively. They are joined in parallel to each other. Obtain the formula for the equivalent emf of this combination of cells.
Derive the formula for the intensity of electric field on the bisector (equatorial line) of an electric dipole.
What is meant by mass-defect? In a nuclear fission reaction, find out the value of the fission energy \( Q \).
Write down the formula for the force in vector form, acting on a moving charged particle in a uniform electric and magnetic fields. Obtain the formula for the radius of the path of the particle entering perpendicular to the magnetic field only. What is the law for the direction of force acting on the particle?
Draw a graph between de Broglie wavelength (\(\lambda\)) and momentum (\(p\)) of a moving particle. A proton and an \(\alpha\)-particle are accelerated by the same potential. Compute the ratio of their de Broglie wavelengths.
Explain the working of a forward biased (\( p - n \)) junction diode by making circuit diagram and by drawing its \( V - I \) characteristic graph. Define its dynamic resistance.
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.