Halite or sulfur or gold or silver
Electrostatic potential energy of a system of charge is given by

here we have
= two charges of different magnitudes
r = distance between charges
so here we can see that electrostatic potential energy will depends upon the product of two charges and inversely depends upon the distance between the two charges
So here we can say that the electrostatic potential energy of two charges will be same and equal to each other
Answer:
Explanation:
Given that,
Number of extra electrons, n = 21749
We need to find the net charge on the metal ball. Let Q is the net charge.
We know that the charge on an electron is
To find the net charge if there are n number of extra electrons is :
Q = n × q
So, the net charge on the metal ball is
. Hence, this is the required solution.
Answer: 
Explanation:
Given
Cross-sectional area of wire 
Extension of wire 
Extension in a wire is given by

where, 

for same force, length and material

Divide (i) and (ii)

Answer:
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Science involves observation and experimentation.
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