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

Represent diagrammatically how the incident planar wavefronts of wavelength λ pass through an aperture of size d, when d is approximately equal to λ.

An electrical bulb is marked 200V, 100W. Calculate the electrical resistance of its filament. If five such
bulbs are connected in series to a 200V supply, how much current will flow through them?

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)

What is meant by the drift speed of free electrons?

Explain the following term:

Intrinsic semiconductor

In Bohr’s model of the hydrogen atom, the radius of the first orbit of an electron is r₀ . Then, the radius of the third orbit is:

a) `r_0/9`

b) `r_0`

c) `3r_0`

d) `9r_0`

if `E_p` and `E_k` represent potential energy and kinetic energy respectively, of an orbital electron, then, according to B9hr's theory:

a)`E_k = -E_p"/"2`

b) `E_k = -E_p`

c) `E_k = -2E_p`

d) `E_k = 2E_p`

On the basis of Bohr's theory, derive an expression for the radius of the n^th orbit of an electron of the hydrogen atom.

State any two Bohr’s postulates and write the energy value of the ground state of the hydrogen atom. 

In which of the following systems will the wavelength corresponding to n = 2 to n = 1 be minimum?

According to Bohr, 'Angular momentum of an orbiting electron is quantized'. What is meant by this statement?

If l₃ and l₂ represent angular momenta of an orbiting electron in III and II Bohr orbits respectively, then l₃: l₂ is :

Calculate angular momentum of an electron in the third Bohr orbit of a hydrogen atom.

Draw energy level diagram for a hydrogen atom, showing the first four energy levels corresponding to n=1, 2, 3 and 4. Show transitions responsible for:
(i) Absorption spectrum of Lyman series.
(ii) The emission spectrum of the Balmer series.

How are various lines of Lyman series formed? Explain on the basis of Bohr’s theory.

State how a p-type semiconductor will be obtained from a pure crystal of a semiconductor.

Explain the following term:

Extrinsic semiconductor

If the radius of first electron orbit in hydrogen atom be r then the radius of the fourth orbit ill be ______.

The energy of an electron in an excited hydrogen atom is - 3.4 eV. Calculate the angular momentum of the electron according to Bohr's theory. (h = 6.626 × 10^-34 Js)

Distinguish between n-type and p-type semiconductors.