The electric field strength at a certain distance from an isolated alpha particle is 3.0 × 107 N C-1.

Question 28

The electric field strength at a certain distance from an isolated alpha particle is 3.0 × 10⁷ N C^-1.

What is the force on an electron when at that distance from the alpha particle?

A 4.8 × 10^-12 N

B 9.6 × 10^-12 N

C 3.0 × 10⁷ N

D 6.0 × 10⁷ N

Reference: Past Exam Paper – March 2016 Paper 12 Q28

Solution:

Answer: A.

Electric field due to alpha particle: E = 3.0×10⁷ N C^-1

Electric force on electron: F = Eq

where E is the field due to the alpha particle and q is the charge of the electron

F = Eq = (3.0×10⁷) × 1.6×10^-19

F = 4.8×10^-12 N