ISC (Science) ISC Class 12 - CISCE Question Bank Solutions for Physics (Theory)

Name the radiation which can be detected by thermopile.

What is meant by the drift speed of free electrons?

To which regions of the electromagnetic spectrum do the following wavelengths belong: 
(a) 250 nm 
(b) 1500 nm 

Arrange the following electromagnetic waves in increasing order of their frequencies (i.e. begin with the lowest frequency):
Visible light, y rays, X rays, microwaves, radio waves, infrared radiations, and ultraviolet radiation.

Name the part of the electromagnetic spectrum which is: 
Suitable for radar systems used in aircraft navigation.

Name the part of the electromagnetic spectrum which is: 
Produced by bombarding a metal target with high electrons.

Calculate the shortest wavelength of electromagnetic radiation present in Balmer series of hydrogen spectrum.

Write balancing condition of a Wheatstone bridge.

Name the electromagnetic radiation whose frequency is 10 Hz.

What is the speed of radio waves in vacuum?

What happens when an electron collides with a positron?

Name the electromagnetic radiation that has been used in obtaining the image below.

What is the wavelength range of electromagnetic radiation used in radio broadcast?

In an atom X, electrons absorb the energy from an external source. This energy “excites” the electrons from a lower-energy level to a higher-energy level around the nucleus of the atom. When electrons return to the ground state, they emit photons.

The figure below is the energy level diagram of atom X with three energy levels, E₁ = 0.00eV, E₂ = 1.78eV and E₃ = 2.95eV. The ground state is considered 0 eV for reference. The transition of electrons takes place between levels E₁ and E₂.

1. What wavelength of radiation is needed to excite the atom to energy level E₂ from E₁?
2. Suppose the external source has a power of 100 W. What would be the rate of photon emission?

Define equipotential surface. 

What is meant by an equipotential surface?

An I0m long uniform metallic wire having a resistance of 20Ω IS used as a  potentiometer wire. This wire is connected in series with another resistance of 480Ω
and a battery of emf 5V having negligible internal resistance. If an unknown emf e is balanced across 6m of the potentiometer wire, calculate

1) the potential gradient across the potentiometer wire

2) the value of the unknown emf e.

Using Ampere's circuital law, obtain an expression for the magnetic flux density 'B' at a point 'X' at a perpendicular distance 'r' from a long current-carrying conductor.
(Statement of the law is not required).

Using Ampere’s circuital law, obtain an expression for magnetic flux density ‘B’ at a point near an infinitely long and straight conductor, carrying a current I.

A meter bridge is balanced with a known resistance (R) in the left hand gap and an unknown resistance (S) in the right hand gap. Balance point is found to be at a distance of 1 cm from the left hand side. When the battery and the galvanometer are interchanged, balance point will ______.