List of top Questions asked in UP Board XII- 2026

Give the postulates of Bohr's atomic model and draw the energy level diagram for the first three lines of the Balmer series in the hydrogen atomic spectrum.
Give Einstein's equation for photoelectric emission. The work function of a metal is 4.2 eV. Electrons are emitted due to light of wavelength 2000 Å. Find the stopping potential for the emitted electrons.
Assuming Earth as a spherical conductor of diameter 12,800 km, calculate its capacity.
Write the formula relating the radius and mass number of a nucleus and show that nuclear density does not depend on the mass number.

Find the readings of the voltmeter and ammeter in the given AC circuit. Is the circuit in the state of resonance?
Given: \( V = 135\sqrt{2}\,\sin 100t \) volt, \( R = 45\,\Omega \), \( X_L = 4\,\Omega \), \( X_C = 4\,\Omega \). The voltmeter is connected across the series L-C combination and the ammeter is in series with the circuit.
A non-conducting cylinder is placed inside the electric field (E). The axis of the cylinder is parallel to the electric field. How much will be the total electric flux passing through the cylinder?
What is displacement current? How is displacement current different from conduction current?
State the result obtained from Rutherford's \(\alpha\)-particle scattering.
If electric field lines are mutually intersecting, then what is the meaning indicated?
From which part of the atom are radioactive radiation emitted?
The wavelength of the de-Broglie wave associated with a moving particle does not depend on:
Write formula for the position of minima in the diffraction pattern of a single slit.
Mainly on which factor does the stability of a nucleus depend?
A convex and a concave lens are placed in contact. The focal lengths \( (F) \) of both are the same. The combination will behave:
A narrow electron beam passes undeviated through an electric field of \( 4\times10^{4}\ \text{V/m} \) and a magnetic field \( 2\times10^{-3}\ \text{weber/m}^2 \) applied at the same place. The speed of the electron beam will be:
Resistances of \( 10\ \Omega \) and \( 15\ \Omega \) are connected in parallel. The combination is connected with a battery of \( V \) volt. Choose the correct statement.
Two electrons in air are at a distance of 1 m. Gravitational and electrostatic forces acting between them are \( F_1 \) and \( F_2 \) respectively. If the dielectric constant of the medium between them becomes infinite, then:
In photoelectric emission, the value of the saturation current depends on:
Find the unit vector perpendicular to each of the vectors (\( \vec{a} + \vec{b} \)) and (\( \vec{a} - \vec{b} \)) where \[\vec{a} = \hat{i} + \hat{j} + \hat{k}, \, \vec{b} = \hat{i} + 2\hat{j} + 3\hat{k}.\]
Show that the function \( f(x) = 7x^2 - 3 \) is an increasing function when \( x>0 \).
The radius of an air bubble is increasing at the rate of \(\frac{1}{2} \, \text{cm/s}\). At what rate is the volume of the bubble increasing while the radius is 1 cm?
If three vectors \(\vec{a}\), \(\vec{b}\) and \(\vec{c}\) satisfying the condition \(\vec{a} + \vec{b} + \vec{c} = 0\). If \(|\vec{a}| = 3\), \[|\vec{b}| = 4 \text{ and } |\vec{c}| = 2, \text{ then find the value of } \vec{a} \cdot \vec{b} + \vec{b} \cdot \vec{c} + \vec{c} \cdot \vec{a}.\] 5
Prove that (4, 4, 2), (3, 5, 2) and (-1, -1, 2) are vertices of a right angle triangle.
Find the general solution of differential equation \( ydx + (x - y^2)dy = 0 \).
If \( f : \mathbb{R} \to \mathbb{R} \) and \( g : \mathbb{R} \to \mathbb{R} \) be functions defined by \( f(x) = \cos x \) and \( g(x) = 3x^2 \) respectively, then prove that \( g \circ f \neq f \circ g \).