List of top Questions asked in UP Board XII

What is the difference between nuclear fission and nuclear fusion? Explain each of them with the help of an appropriate example. Why is in both incidents the nuclear energy released?

Focal length of each lens is 10 cm as shown in the given figure. Find the distance of the image of point object O from the convex lens and also draw the ray diagram. If both lenses are placed in contact, what will be the power of the combined lens?

State the required conditions for the interference of light. Find the value of maximum resultant intensity of two waves having intensities \( I \) and \( 4I \), when sources are (i) coherent and (ii) non-coherent.

A monochromatic ray of light is incident at an angle of \( 45^\circ \) on the face AB of a right-angled prism (\( A = 90^\circ \)), as shown in the figure. The emergent ray is refracted tangentially from the face AC. Find out the refractive index of the prism material.

What are Kirchhoff's two laws for the electrical circuit? Find out the reading of the ammeter with the help of the given circuit, while its resistance is negligible.

In the given circuit, A.C. source is given by: \[ V = 282 \sin (100 \pi t) \text{ volt} \] The internal resistance of the source is \( 2000 \, \Omega \).

Find out:

(i) rms value of source voltage
(ii)inductive reactance of the circuit
(iii) impedance of the circuit

Find the magnitudes of currents \( i_1 \), \( i_2 \), and \( i \) with the help of the given circuit, when (i) just at the moment switch S is pressed and (ii) S is pressed for a long time.

Current of 5 mA is flowing in the given circuit. Find the value of the resistor \( R \).

Whether the \( p\text{-}n \) junction diode is forward biased or reverse biased in the given figure.

Currents of 10 A and 20 A are passed in two long parallel wires A and B, as shown in the figure. A wire C of 15 cm length is placed just in between these two wires, in which 5 A of current is passed. Then what will be the force acting on the wire C?

(i) Calculate the number of turns in the secondary coil.

(ii)Input power.

A graph is shown between the maximum kinetic energy (\( E_k \)) of emitted photoelectrons and frequency (\( \nu \)) of the incident light in an experiment of the photoelectric effect. Find:
(i) Threshold frequency
(ii) Work function (in eV)
(iii) Planck's constant

What is the magnitude of the current \( i \) in the given circuit?

Which of the following ray diagrams is correct, when \( n_1 \) is the refractive index of the medium and \( n_2 \) is of the lens material (\( n_1>n_2 \))?

Calculate the following for the given circuit:

What are forward biasing and reverse biasing in \( p\text{-}n \) junction? Explain the difference between forward current and reverse current.

Compare features of p-type and n-type semiconductors. Draw circuit diagram of half-wave rectifier of p-n junction diode and explain it.

In a circuit, the equation for alternating voltage \( V \) is represented by \( V = 40 \sin(100 \pi t) \) volt. Here \( t \) is in seconds. Draw the time-voltage (t-V) graph with proper scale for one cycle. Calculate the root mean square value of voltage.

By drawing a ray diagram, explain the formation of image in a compound microscope. Establish the formula for magnifying power for it.

What are electromagnetic waves? Draw their propagation diagram. Show the electric field amplitude and magnetic field amplitude in the propagation diagram.

Derive the formula for the torque acting on a current-carrying loop in a uniform magnetic field and define the magnetic dipole moment with the help of it.

What is meant by a resonant circuit? Write down the required conditions for the L-C-R series resonant circuit and expression for the frequency in the state of resonance.

Explain the difference between the following substances with the help of examples:

(i) Paramagnetic
(ii) Diamagnetic
(iii) Ferromagnetic