Atomic and Nuclear Physics Answers

Two equal charges are separated 75cm apart in free air. Calculate the quantity of either charge if the force between them is 0.17N. What will be the quantity if the charges are situated in an insulating medium of dielectric constant 10?

Derive the expression of the Q = ΔE of a nuclear reaction, hence, determine the Q value and the nature of the reaction F19 (H1,α) O16( 18.998405u, 15.994915u, 4.002603u, 1.007825u are masses of F19, O16, α, H1) respectively.

a ii). Discuss the primary processes by which gamma rays interact with matter

b). The Q value of the Na23 (n,α) F20 reaction is -5.4MeV. Determine the threshold energy of the neutrons for this reaction (22.9898u, 18.9964u, 4.0039u, 1.008665u are the masses of Na23, F20 α and n respectively).

Charge q1 = 7.00 μC is at the origin, and charge q2 = -5.00 μC is on the x-axis, 0.300 m from the origin as shown below. (a) Find the magnitude and direction of the electric field at point P, which has coordinates (0, 0.400) m. (b) Find the force on a charge of 2.00 × 10-8 C placed at P

Problem - A sample of gallium arsenide (GaAs) is doped with 1010 silicon atoms per cm3

.

Ninety-five percent of the silicon atoms replace arsenic atoms and the remaining five percent

replace gallium atoms. T = 300 K. The intrinsic carrier concentration, ni

, is equal to 9 × 106 cm3

.

Calculate the electron and hole concentration as well as the position of the Fermi level.

Problem – A silicon wafer is doped with 2×1016 boron and 1016 phosphorus atoms per cm3

.

Calculate n, p, and EF at room temperature assuming complete ionization. Repeat the same for 8

x 1015 boron atoms per cm3

and 1016 phosphorus atoms per cm3

.

Problem-The intrinsic temperature of a semiconductor is the temperatures at which the intrinsic

carrier concentration equals the impurity concentration. Find the intrinsic temperature for a

silicon sample doped with 1015 phosphorus atoms/cm3

.

Problem - Determine the total number of energy states in silicon between E, and E + kT at T = 300 K.

A spring has a force constant of 80 N/m, it vibrates with a frequency of 7 Hz.

Calculate the,

a) period;

b) angular frequency;

c) mass of the spring.

find the fermi energy of copper by assuming that each copper atom contributes one free electron to the electron gas . the density of copper is 8.94 x 10^3kg/m^3

In a radioactive decay, a nucleus of mass 4.0 × 10-25kg initially at rest emitted an a-particle of mass 6.7 x 10-27kg with a velocity of 1.5 x 107 ms-¹.

a Calculate the velocity of recoil of the nucleus.

b Calculate the kinetic energy of:

1 the recoil nucleus,

ii the o-particle.