The charge of magnitude 1.6 x 10 ^ -19 C is placed in a uniform electric field of intensity 1200Vm ^ -1…

Analyze the question: A charged particle (it is an electron, going by the charge and mass) sits in a uniform electric field. The field exerts a force on it, which causes acceleration.

Concept:

• Force on a charge in an electric field: F = qE
• Newton's second law: F = ma
• Combining them: a = qE/m

Solution:

Given:

• q = 1.6 × 10⁻¹⁹ C
• E = 1200 V/m
• m = 9.1 × 10⁻³¹ kg

Step 1: Find the force F = qE = (1.6 × 10⁻¹⁹)(1200) = 1.92 × 10⁻¹⁶ N

Step 2: Find the acceleration a = F/m = (1.92 × 10⁻¹⁶) / (9.1 × 10⁻³¹)

a = (1.92 / 9.1) × 10^(−16+31) = 0.211 × 10¹⁵ = 2.11 × 10¹⁴ m/s²

Answer: The acceleration is 2.11 × 10¹⁴ m s⁻², which is option A.

Tip: Be careful with the powers of 10. 1.92/9.1 gives 0.211, not 2.11, so you must shift the decimal and raise the exponent from 10¹³ to 10¹⁴. This is where options A and B trap students. Also, a quick check: the electron's charge-to-mass ratio is about 1.76 × 10¹¹ C/kg, and multiplying by 1200 gives about 2.11 × 10¹⁴, which is a useful shortcut.