Numerical problems on electric potential energy

In this post, we will solve Numerical problems on electric potential energy. [Electric potential energy is also known as electrical potential energy]

Numerical Problem based on electrical potential energy

Suppose a charge of 5.60 x 10−3 C is placed at one end of the 8.37 km sandcastle, while an unspecified charge is placed at the opposite end. If the electrical potential energy associated with these charges is –50.5 J, what is the quantity of the second charge?

Solution:

PEelectric = −50.5 J
q2 = 5.60 × 10−3 C

r = 8.37 km = 8.37 × 103 m
kC = 8.99 × 109 N•m2/C2

Unknown: q1 =?

We will use the equation for the electrical potential energy associated with a pair of charges.

q1 =r PEelectric / kC q2

=> q1= (8.37 × 103 ) (−50.5) / (8.99 × 109 ) (5.60 × 10−3 ) C

= 8.40 × 10−3 C

The quantity of the second charge = 8.40 × 10−3 C

Numerical problems on electric potential energy
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