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

State Moseley's law

With the help of a labelled diagram, show that the balancing condition of a Wheatstone bridge is

`R_1/R_2 = R_3/R_4` where the terms have their usual meaning.

In a conductor 6.25 × `10^16` electrons flow from its end A to B in 2 s. Find the current flowing through the conductor (e = 1.6 × `10^-19` C)

Obtain the balancing  condition for the Wheatstone bridge arrangements as shown in Figure 4 below:

State the name and the range of wavelength of the invisible electromagnetic waves beyond the red end of the visible spectrum.

Name three radiations and their wavelength range which are invisible and beyond the violet end of the visible spectrum.

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?