Home
Class 11
PHYSICS
A tiny spherical oil drop carrying a net...

A tiny spherical oil drop carrying a net charge q is balanced in still air with a vertical uniform electric field of strength `(81pi)/(7)xx10^5Vm^-1`. When the field is switched off, the drop is observed to fall with terminal velocity `2xx10^-3ms^-1`. Given `g=9.8ms^-2`, viscoisty of the air `=1.8xx10^-5Nsm^-2` and the denisty of oil `=900kg m^-3`, the magnitude of q is

A

`1.6 xx 10^(-19)C`

B

`3.2 xx 10^(-19)C`

C

`4.8 xx 10^(-19)C`

D

`8.0 xx 10^(-19)C`

Text Solution

Verified by Experts

The correct Answer is:
D
In equilibrium,
`mg = qE`
in absence of electric field,
`mg = 6pietarv`
`rArr qE = 6piqrv`
`m = (4)/(3)piRr^(3)d. = (qE)/(g)`
`(4)/(3)pi((qE)/(6pietav))^(3)d = (qE)/(g)`
After substituting value we get,
`q = 8 xx 10^(-19)C`
Promotional Banner

Topper's Solved these Questions

  • ELASTICITY AND VISCOCITY

    RESONANCE|Exercise Exercise- 3 PART - IV|9 Videos

  • ELASTICITY AND VISCOCITY

    RESONANCE|Exercise Advanced Level Problems|9 Videos

  • ELASTICITY AND VISCOCITY

    RESONANCE|Exercise Exercise- 2 PART - III|11 Videos

  • DAILY PRACTICE PROBLEMS

    RESONANCE|Exercise dpp 92 illustration|2 Videos

  • ELECTROMAGNETIC INDUCTION

    RESONANCE|Exercise Exercise|43 Videos

Similar Questions

Explore conceptually related problems

The terminal velocity of a rain drop is 30cm//s . If the viscosity of air is 1.8xx10^(-5)Nsm^(-2) .The radius of rain drop is

An oil drop falls through air with a terminal velocity of (5xx10^(-4))/(sec) viscosity of air is 1.8xx10^(-5)(N-s)/(m^(2)) and density of oil is 900 kg m^(3) neglect density of air as compared to that of oil.

If an oil drop of weight 3.2xx10^(-13) N is balanced in an electric field of 5xx10^(5) Vm^(-1) , find the charge on the oil drop.

A rain drop of radius 0.5 mm has a terminal velocity in air 2 ms^(-1) . The viscosity of air is 18 xx 10^(-5)" dyne "cm^(-2)s . Find the viscous force on the rain drop.

Find the terminal velocity of a rain drop of radius 0.01 mm. The coefficient of viscosity of air is 1.8xx10^-5 N-sm^-2 and its density is 1.2kgm^-3 .Density of water =1000kgm^-3 . Take g=10ms^-2

A rain drop of radius 0.3 mm falls through air with a terminal viscosity of 1 m s^(-1) . The viscosity of air is 18 xx 10^(-5) poise. The viscous force on the rain drop is

Find the manitude of a charge whose electric field strength is 18 xx 10^(3) N C^(-1) at a distance of 5 m in air .

A negatively charged oil drop is prevented from falling under gravity by applying a vertical electric field of 100Vm^(-1) . If the mass of the drop is 1.6xx10^(3)g the number of electrons carried by the drop is (g=10ms^(-2))