Question

A point charge of 4.0 µC is placed at a distance of 0.10 m from a hard rubber rod with an electric field of 1.0 × 103 . What is the electric potential energy of the point charge?
× 10–4 J

What is the electric potential energy of the point charge at 1.3 m?


× 10–3 J

Answer 1

The electric potential energy of the point charge is 4.

the electric potential energy of the point charge at 1.3 m is 5.2.

Answer 2

Answer:

Part 1)

$U = 4 \times 10^{-4} J$

Part 2)

$U = 5.2 \times 10^{-3} J$

Explanation:

Electric field due to rubber rod is given by

$E = 1.0 \times 10^3 N/c$

now we also know that

$V = E. r$

$V = (1.0 \times 10^3)(0.10)$

$V = 1.0 \times 10^2$

now potential energy is given as

$U = qV$

$U = (4 \mu C)(1.0 \times 10^2)$

$U = 4 \times 10^{-4} J$

Similarly the electric potential at distance r = 1.3 m

so we have

$V = (1.0 \times 10^3)(1.3)$

$V = 1.3 \times 10^3 Volts$

now potential energy is given as

$U = (4\mu C)(1.3 \times 10^3)$

$U = 5.2 \times 10^{-3} J$