The work done by the battery is equal to the charge transferred during the process times the potential difference between the two terminals of the battery:

where q is the charge and

is the potential difference.
In our problem, the work done is W=39 J while the potential difference of the battery is

, so we can find the charge transferred by the battery:
Answer:
(a) 0.345 T
(b) 0.389 T
Solution:
As per the question:
Hall emf, 
Magnetic Field, B = 0.10 T
Hall emf, 
Now,
Drift velocity, 

Now, the expression for the electric field is given by:
(1)
And

Thus eqn (1) becomes
where
d = distance
(2)
(a) When 

(b) When 

Answer:
5x10^-3
Explanation:
Hooke's Law states that the force needed to compress or extend a spring is directly proportional to the distance you stretch it.
Hooke's Law can be represented as
<h3> F = kx, </h3>
<em>where F is the force </em>
<em> k is the spring constant</em>
<em> x is the extension of the material </em>
<em />
Plug values in the equation
Step 1 find the original extension
0.045 = (400)x
x = 1.125x 10^-4 m d
Step 2 find the new extension
0.045+2 = 400(x)
2.045 = 400x
x = 5.1125x10^-3
Step 3 subtract the new extension with original
Total extension of the spring = 5.1125x10^-3 - 1.125x 10^-4 m = 5x10^-3
Answer:
f =ma = 0.015 * 55 = 0.825 N
so yeah that's ur ans