Question1
Suppose that for some process the cross section for absorption of a certain wavelength photon is 10^-16 cm2, and the density of H is 1 g/cm^3.
(a) Assume we have a cylinder that is 1 m long and has an end area of 1 cm^2. What is total absorption cross section? How does this compare with the area of the end?
(b) What is an absorption coefficient (per unit length)?
(c) What is mean free path?
(d) How long a sample of material is needed to produce an optical depth of unity?
Question2
The total impedance of an RC circuit with a resistance of 200 Ω is 1060 Ω. If frequency of the applied voltage is 20.0 Hz, what is value of the capacitance in this circuit?
A) 6.64 μF
B) 7.64 μF
C) 8.64 μF
D) 9.64 μF
E) 200 μF
Question3
A magnetic field is perpendicular to a 0.060-m x 0.080-m rectangular coil of wire that has 120 turns. In a time of 0.040 s, an average emf of magnitude 1.4 V is induced in the coil. What is magnitude of the change in the magnetic field?