Question

A vertical electric field of magnitude 4.9 × 105 N/C just prevents a water droplet of a mass of 0.1 g from falling. The value charge on the droplet will be(Given g = 9.8 m/s2)

• A. 1.6 × 10-9 C
• B. 2.0 × 10-9 C
• C. 3.2 × 10-9 C
• D. 0.5 × 10-9 C

Answer 1

Answer: (B)

2.0 × 10-9 C

Answer 2

Since the droplet is at rest
⇒ Net force = 0
⇒ mg = qE
⇒ q=$\frac{mg}{E}$=2×10-9 C
The correct option is (B) : 2.0 × 10–9 C