List of top Questions asked in UP Board XII

Electric force of 80 N acts between two point charges. When these charges are placed in a dielectric medium, then electric force becomes 8 N. Dielectric constant of the medium will be

What is meant by the concept of matter-wave of de Broglie ? Establish the relation for de Broglie wavelength in terms of kinetic energy.

The work function of photoelectric surface is 4.0 eV. Radiation of frequency \(3 \times 10^{15}\) Hz is incident on it. Calculate the maximum velocity of emitted photo-electron.

What is the solenoid ? Obtain the expression for magnetic field inside a long current carrying solenoid.

Describe in brief, the \(\alpha\)-scattering experiment. Write down about the atomic-structure from the observation obtained from the experiment.

How is the p-n junction diode used as the full wave rectifier ? Explain its working by drawing simple circuit.

Establish the formula for focal length of combination of two thin lenses placed in contact.

Establish the relation between the resistances of arms of wheatstone bridge in balance conditions.
OR
The ratio of lengths and masses of three wires of same metal are 3 : 2 : 1 and 1 : 2 : 3 respectively. Find the ratio of resistances of those wires.}

What is meant by interference and diffraction of light ? Write the conditions of interference.

What is the principle of transformer ? Explain the working of step-up transformer by drawing circuit diagram.

Explain the classification of conductors, insulators and semiconductors on the basis of energy bands.

Differentiate between paramagnetic, diamagnetic and ferromagnetic substances by giving one example of each.

Draw a ray diagram of reflecting telescope. Explain its working.

The light rays are incident on a convex lens as in figure. If focal length of lens is 20 cm then find the position of image. Show ray diagram as well.