Question

A dust particle of mass 10^–3 g is stationary between the plates of a horizontal parallel plate capacitor of 0.016 m separation which is connected to a voltage of 100V. How many fundamental charges (e = 1.6 × 10^–19 C) the dust particles carries?

• A. 1
• B. 10¹⁰
• C. 100
• D. 1000

Answer 1

Answer: (D)

1000

Answer 2

Q V_B = V_D = V_­E = 10 V

\ line BD is equipotential surface

\ electric field will be perpendicular to line BD

\ E = $\frac { \Delta \mathrm { V } } { \mathrm { d } }$ = = $\frac { 10 - 5 } { \frac { \sqrt { 2 } } { \sqrt { 2 } } \times 10 ^ { - 2 } }$ = 500 V/m