Science (English Medium) Class 12 - CBSE Question Bank Solutions for Physics

An ideal inductor is connected across an AC source of voltage. The current in the circuit ______.

The wavelength of the second line of the Balmer series in the hydrogen spectrum is 4861 Å. Calculate the wavelength of the first line of the same series.

What is the ratio of inductive and capacitive reactance in an ac circuit?

Calculate the binding energy of an alpha particle in MeV. Given

mass of a proton = 1.007825 u

mass of a neutron = 1.008665 u

mass of He nucleus = 4.002800 u

1u = 931 MeV/c²

The energy of an electron in the n^th orbit of the hydrogen atom is E_n = -13.6/n²eV. The negative sign of energy indicates that ______.

Show that the least possible distance between an object and its real image in a convex lens is 4f, where f is the focal length of the lens.

Define the term drift velocity.

In what way is the behaviour of a diamagnetic material different from that of a paramagnetic, when kept in an external magnetic field?

Define modulation index.

Derive an expression for  drift velocity of free electrons.

Define an equipotential surface.

What is its relation with relaxation time?

Draw a sketch of equipotential surfaces due to a single charge (-q), depicting the electric field lines due to the charge

Write its (‘mobility’ of charge carriers) S.I. unit

Given the ground state energy E₀ = - 13.6 eV and Bohr radius a₀ = 0.53 Å. Find out how the de Broglie wavelength associated with the electron orbiting in the ground state would change when it jumps into the first excited state.

State three important factors showing the need for translating a low frequency signal into a high frequency wave before transmission

Draw a sketch of a sinusoidal carrier wave along with a modulating signal and show how these are superimposed to obtain the resultant amplitude modulated wave

State Lenz's law. Illustrate, by giving an example, how this law helps in predicting the direction of the current in a loop in the presence of a changing magnetic flux.

Define the term 'intensity of radiation' in terms of photon picture of light.

How are side bands produced?