Solution

Solution

Two important processes involved during the formation of p-n junction are diffusion and drift.

Formation of depletion region and barrier potential: At the instant of p-n junction formation, the free electrons near the junction diffuse across the junction into the p region and combines with holes. Thus, on combining with the hole, it makes a negative ion and leaves a positive ion on n-side. These two layers of immobile positive and immobile negative charges form the depletion region.
When electrons diffuse across the junction, a point is reached where the negative charge repels any further diffusion of electrons. This depletion region now acts as a barrier. Now the external energy is supplied to get the electrons to move across the barrier of electric field. The potential difference required to move the electrons through the electric field is called barrier potential.

Solution

(a)Suppose the positive ion with charge q moves in a dee with a velocity v, then
mv^2/r=qvB
r=mv/qB
where m is the mass and r is the radius of the path of ion in the dee and B is the strength of the magnetic field. The time taken by the ion,
T=2πr/v
1/f=2πr/v
f=v/2πr
f=qB/2πm
This frequency is called the cyclotron frequency.
(b) Deuteron and proton have different masses and cyclotron on frequency depends inversely on mass. Hence, both cannot be accelerated with the same oscillator frequency.

Solution

The work function of Na and K is less than the energy of incident radiation. Therefore, Na and K will cause photoelectric emissions while Mo and Ni will not cause photoelectric emissions. There will be no effect on photoelectric emission if the source is brought nearer and placed at 50cm.

Solution

Solution

Amplitude Modulation is the process in which the amplitude of high frequency carrier wave changes in accordance with the instantaneous value of modulating signal.
Two factors which justify the need for modulating a low frequency base-band signal:
(i)Modulation is necessary to keep the dimension of receiving antenna within practical limit. Length of antenna bears inverse relation with the frequency of signal it receives. Hence, frequency is kept high to keep anteena length in practical limits.
(ii)Size of antenna should be comparable to wavelength for audio frequency signal.

Solution

(a)

Solution

(a) Consider a point P on broad side position of dipole formed of charges +q and -q at separation 2l. The distance of point P from mid point (O) of electric dipole is r. Let E₁ and E₂ be the electric field strengths due to charges + q and – q of electric dipole.

(b)

Solution

(a)
(b)The process of spontaneous emission of a positron(e⁺) from nucleus is called β⁺ decay.
The process of spontaneous emission of an electron(e⁻) is called β⁻ decay.

Solution