Answer:
a). 87.5 mA or
A
b). 1.78 
Explanation:

n the number of free electrons is 28 in text reference and if they don't give q is take as the charge of electron.
a).
A
b).


Answer:
The rate of change of the shadow length of a person is 2.692 ft/s
Solution:
As per the question:
Height of a person, H = 20 ft
Height of a person, h = 7 ft
Rate = 5 ft/s
Now,
From Fig.1:
b = person's distance from the lamp post
a = shadow length
Also, from the similarity of the triangles, we can write:

Differentiating the above eqn w.r.t t:
Now, we know that:
Rate = 
Thus
. we need like a picture you something what’re you trying to ask
14.59390 kg hope it helps
Its called gauge pressure