An oil drop of radius 2 mm with a density 3 g cm -3 is held stationary under a constant electric field 3.55 × 105 V m -1 in the Millikan's oil drop experiment. What is the number of excess electrons that the oil drop will possess? (consider g =9.81 m / s 2 )

Question

An oil drop of radius 2 mm with a density 3 g cm -3 is held stationary under a constant electric field 3.55 × 105 V m -1 in the Millikan's oil drop experiment. What is the number of excess electrons that the oil drop will possess? (consider g =9.81 m / s 2 ) (A) 48.8 × 1011 (B) 1.73 × 1010 (C) 17.3 × 1010 (D) 1.73 × 1012

Tardigrade Admin · Accepted Answer

qE = Mg neE =ρ((4/3) π r 3) × g n × 1.6 × 10-19 × 3.55 × 105 =3 × 103 × (4/3) × π ×(2 × 10-3)3 × 9.81 n =173 × 10(3-9-5+19) n =1.73 × 1010

Q. An oil drop of radius 2 mm with a density $3 g c m^{- 3}$ is held stationary under a constant electric field $3.55 \times 1 0^{5} V m^{- 1}$ in the Millikan's oil drop experiment. What is the number of excess electrons that the oil drop will possess? (consider $g = 9.81 m / s^{2}$ )

$48.8 \times 1 0^{11}$

$1.73 \times 1 0^{10}$

$17.3 \times 1 0^{10}$

$1.73 \times 1 0^{12}$

$qE = M g$
$n e E = ρ (\frac{4}{3} π r^{3}) \times g$
$n \times 1.6 \times 1 0^{- 19} \times 3.55 \times 1 0^{5}$
$= 3 \times 1 0^{3} \times \frac{4}{3} \times π \times (2 \times 1 0^{- 3})^{3} \times 9.81$
$n = 173 \times 1 0^{(3 - 9 - 5 + 19)}$
$n = 1.73 \times 1 0^{10}$

Q. An oil drop of radius 2 mm with a density 3gcm−3 is held stationary under a constant electric field 3.55×105Vm−1 in the Millikan's oil drop experiment. What is the number of excess electrons that the oil drop will possess? (consider g=9.81m/s2 )

48.8×1011

1.73×1010

17.3×1010

1.73×1012