Calculate the force acting on an electron of charge 1.5 x 10-19C placed in an electric field of intensity 105Vm-1

Analyze the question: We're given a charge and an electric field intensity, and we need the force on the charge.

Concept: The force on a charge q in an electric field of intensity E is

F = qE

Solution:

The question as typed has lost its superscripts, so it reads:

• q = 1.5 × 10⁻¹⁹ C
• E = 10⁵ V/m

Then:

F = qE = (1.5 × 10⁻¹⁹) × (10⁵) F = 1.5 × 10⁻¹⁴ N

Answer: This matches option D (1.

Note on the data: The charge of an electron is actually 1.6 × 10⁻¹⁹ C, but the question gives 1.5 × 10⁻¹⁹ C, so use the value given in the question.

Tip: When multiplying powers of 10, add the exponents: −19 + 5 = −14. For F = qE, just multiply the numbers and add the powers. Always check that the units work: C × V/m = N.