Question

A copper ball of density 8.6 g/cm³, 1 cm in diameter is immersed in oil of density 0.8 glcm³. The charge in µC on the ball, if it remains just suspended in an electric field of intensity 3600 V/m acting in upward direction is ______ µC.

विकल्प

• 30

• 34

• 32

• 35

Answer 1

A copper ball of density 8.6 g/cm³, 1 cm in diameter is immersed in oil of density 0.8 g/cm³. The charge in µC on the ball, if it remains just suspended in an electric field of intensity 3600 V/m acting in upward direction is 34 µC.

Explanation:

For equilibrium

`"qE"+4/3pi"R"^3xxrho_"oil"xx"g"=4/3pi"R"^3xxrho_"Cu"xx"g"`

q = `(4/3pi"R"^3(rho_"Cu"-rho_"oil")"g")/"E"`

q = `(4/3xx3.14xx(0.5xx10^-2)^3(7.8)xx10^3xx10)/3600`

q = `(4/3xx3.14xx7.8xx0.125xx10^-2)/3600`

= 3.4 × 10^–5 C

= 34 × 10^–6 C

= 34.00 µC