Diffusion and Drift are the two processes that take place in the formation of a p-n junction.

In an n-type semiconductor, the concentration of electrons (number of electrons per unit volume) is more compared to the concentration of holes. Similarly, in a P -type semiconductor, the concentration of holes is more than the concentration of electrons. During the formation of p-n junction.

Due to the diffusion of electrons and holes across the junction a region of
(immobile) positive charge is created on the n-side and a region of(immobile) negative charge is created on the p-side, near the junction; this is called depletion region.

Barrier potential is formed due to loss of electrons from n-region and gain of electrons by p-region. Its polarity is such that it opposes the movement of charge carriers across the junction.

When a charged particle (q) moves inside a magnetic field B with velocity v, it experiences a force F = q(v xB) when v is perpendicular to B, the force F on the charged acts as the centripetal force and makes it move along a circular path.
Let m be the mass of particle and r is radius  of circular path



Time period of the circular motion of a charged particle is given by


ii) No, The mass of the two particles, i.e deuteron and proton, is different.Since (cyclotron) frequency depends inversely on the mass, they cannot be accelerated by the same oscillator frequency.

Solar cell

1. According to Rutherford model, an electron orbiting around the nucleus continuously radiates energy due to the acceleration; hence the atom will not remain stable.
2. As electron spirals inwards; its angular velocity and frequency change continuously; therefore it will emit a continuous spectrum.

Magnifying power is defined as the angle subtended at the eye by the image
to the angle subtended (at the unaided eye) by the object.

To increase the magnifying power both the objective and eyepiece must have short focal lengths such as  

It is the distance of charged particle from the centre of the nucleus, at
which the whole of the initial kinetic energy of the (far off) charged
particle gets converted into the electric potential energy of the system.
Distance of closest approach (r_c) is given by


(r_c) is inversely proportional to K. Thus,
‘K’ is doubled therefore r_c becomes r/2

The electric current will remain constant in a wire whose cross-sectional area is increased linearly from its one end to the other, is connected across a battery of V volts.

Because current is the only quantity that does not depend on the area of cross- sections of the wire.
I=dq/dt, that is the rate of flow of charge, where as drift speed, current density and electric field depending on the increasing area of the cross-section of the following relations:

Drift speed: ν_d=I/An_e
Current density = I/A
Electric field = J/σ

Radius of ground state of hydrogen atom =0.53A^°  = 0.53 x10^-10m
According to de Broglie relation 2πr = nλ
For ground state n=1
2 x 3.14 x 0.53 x 10^-10= 1 x λ
therefore, λ = 3.32 x10^-10 m
= 3.32 A^° 

Here, A = 200 cm²
N=20
ω = 50 rad/s
B = 3.0× 10⁻² T
for maximum current emf induced should be maximum.

So, for maximum emf sinωt in e = NAB ω sinωt should be 1.

Hence, e = NABω
e = 20 × 200/10000 × 50 × 3 × 10⁻² = 0.6 V

Since resistance of the circular loop is not given, let us consider its resistance to be R.

Therefore, current I in the coil is

There are two basic modes of communication which are used in satellite communication:

(i) point-to-point and broadcast-  In the broadcast mode, there are a large number of receivers corresponding to a single transmitter. Satellite communication is an example of the broadcast mode of communication.

(ii) Space wave mode of propagation: In the frequency range 30 MHz to 1000 Mhz, the wavelengths are in the range of 30 cm to 10 m. At these wavelengths the diffraction of waves is high and the waves lose their directional property. So frequency range of 5.925 - 6.425 GHz is used in satellite communication.