Electric Potential Energy - NEET Physics Questions
ā† Back to Electrostatics

Electric Potential Energy

Practice Questions:
Question 11: moderate

If an electron is accelerated from rest through a potential difference V, then its final speed is proportional to :

1. V
2. VĀ²
3. āˆšV
4. 1/V
View Answer

The kinetic energy gained by the electron is equal to the work done by the electric field:

\[
eV = \frac{1}{2} m v^2
\]

Rearranging for \(v\):

\[
v = \sqrt{\frac{2eV}{m}}
\]

This shows that \(v \propto \sqrt{V}\).

šŸ’¬ Discuss this Question
Question 12: easy

An elementary particle of mass m and charge +e is projected with velocity v at a much more massive fixed particle of charge Ze, where Z > 0. What is the closest possible approach of the incident particle?

1. \( \frac{Ze^2}{2\pi\varepsilon_0 m v^2} \)
2. \( \frac{Ze}{4\pi\varepsilon_0 m v^2} \)
3. \( \frac{Ze^2}{8\pi\varepsilon_0 m v^2} \)
4. \( \frac{Ze}{8\pi\varepsilon_0 m v^2} \)
View Answer

At the distance of closest approach \( r_0 \), the kinetic energy is completely converted into electrostatic potential energy: \( \frac{1}{2} m v^2 = \frac{1}{4 \pi \varepsilon_0} \frac{Ze^2}{r_0} \). Rearranging gives \( r_0 = \frac{Ze^2}{2\pi\varepsilon_0 m v^2} \).

šŸ’¬ Discuss this Question