Answer:
a) 
Explanation:
Given paraeters are:
R = 25 cm
d = 4.7 mm
f = 60 Hz
= 160 V
a) 
Where
Hz and
V

For 

Since 

From Ampere's Law:
where 
So at
,

For maximum B, cos(2πft) = 1. Hence,
T
b) From r = 0 to r = R = 0.025 m, by Ampere's Law, the equation will be:

From r = R = 0.025 m to r = 0.1 m, by Ampere's Law, the equation will be:

The plot is given in the attachment.
In order to determine the effect, we will first consider the mathematical expression of Newton's law of gravitation:
F = (Gm₁m₂)/r², where G is the gravitational constant, m represents the mass of a body, and r is the separation between the two bodies.
It is visible that the force is directly proportional to the product of the two masses. Therefore, if one mass is kept constant and the other is tripled, the force will also triple. Thus, the force will be:
26 * 3
= 78 Newtons
It's obvious that 65 s isn't the answer. I'm still doing this question myself
Crust sitting on top of Milton rock of the mantle
I don't personally know the answer, but this article should help!
http://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-a-black-hole-58.html