(a) 
The radiation pressure exerted by an electromagnetic wave on a surface that totally absorbs the radiation is given by

where
I is the intensity of the wave
c is the speed of light
In this problem,

and substituting
, we find the radiation pressure

(b) 
Since we know the cross-sectional area of the laser beam:

starting from the radiation pressure found at point (a), we can calculate the force exerted on a tritium atom:

And then, since we know the mass of the atom

we can find the acceleration, by using Newton's second law:

The answer is the fourth choice because there are 7 represents in a coefficient.
Answer:
Self inductance, 
Explanation:
It is given that,
Length of the coil, l = 5 cm = 0.05 m
Area of cross section of the coil, 
Number of turns in the coil, N = 130
The self inductance relates the magnetic flux linkage to the current through the coil and it is given by :


L = 0.000127 Henry
or

So, the self inductance of the coil is 127 microhenry. Hence, this is the required solution.
Hey, Sissy05pooh!
The more domains that are aligned in a magnet it is stronger, and the magnetic field is larger.