Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Physics

Draw a schematic sketch showing how amplitude modulated signal is obtained by superposing a modulating signal over a sinusoidal carrier wave.

Draw equipotential surfaces:

(1) in the case of a single point charge and

(2) in a constant electric field in Z-direction. Why are the equipotential surfaces about a single charge not equidistant?

(3) Can electric field exist tangential to an equipotential surface? Give reason

Write two advantages of frequency modulation over amplitude modulation.

State Bohr's postulate to define stable orbits in the hydrogen atom. How does de Broglie's hypothesis explain the stability of these orbits?

Using Bohr's postulates, derive the expression for the orbital period of the electron moving in the n^th orbit of hydrogen atom ?

State Bohr postulate of hydrogen atom that gives the relationship for the frequency of emitted photon in a transition.

Using Bohr's postulates, derive the expression for the total energy of the electron in the stationary states of the hydrogen atom ?

What is the geometrical shape of equipotential surfaces due to a single isolated charge?

Using Bohr’s postulates, obtain the expressions for (i) kinetic energy and (ii) potential energy of the electron in stationary state of hydrogen atom.

Draw the energy level diagram showing how the transitions between energy levels result in the appearance of Lymann Series.

Write three important factors which justify the need of modulating a message signal. Show diagrammatically how an amplitude modulated wave is obtained when a modulating signal is superimposed on a carrier wave.

Using Bohr’s postulates, obtain the expression for the total energy of the electron in the stationary states of the hydrogen atom. Hence draw the energy level diagram showing how the line spectra corresponding to Balmer series occur due to transition between energy levels.

Using Bohr’s postulates, obtain the expression for total energy of the electron in the n^th orbit of hydrogen atom.

Draw the equipotential surfaces due to an electric dipole. Locate the points where the potential due to the dipole is zero.

Using Bohr’s postulates, derive the expression for the frequency of radiation emitted when electron in hydrogen atom undergoes transition from higher energy state (quantum number n_i) to the lower state, (n_f).

When electron in hydrogen atom jumps from energy state n_i = 4 to n_f = 3, 2, 1, identify the spectral series to which the emission lines belong.

The electron in hydrogen atom is initially in the third excited state. What is the maximum number of spectral lines which can be emitted when it finally moves to the ground state?

Using Bohr’s postulates for hydrogen atom, show that the total energy (E) of the electron in the stationary states tan be expressed as the sum of kinetic energy (K) and potential energy (U), where K = −2U. Hence deduce the expression for the total energy in the n^th energy level of hydrogen atom.

Why is there no work done in moving a charge from one point to another on an equipotential surface?

Using Ampere’s circuital law, obtain the expression for the magnetic field due to a long solenoid at a point inside the solenoid on its axis ?

Write the expression for Bohr’s radius in hydrogen atom ?

Depict the equipotential surfaces for a system of two identical positive point charges placed a distance(d) apart?