Question

What is the capacitance of a 1.0" diameter steel ball-bearing? A. 1.4 pF B. 14 pF C. 140 pF D. Zero, since there is only one conducting surface Capacitance is not defined for a single conducting surface E.

Answer 1

Answer:

option A

Explanation:

steel in a conducting ball of diameter

2 r = 1 '' = 2.54 cm = 2.54 × 10⁻² m

Potential due to conducting steel ball

$V = \dfrac{1}{4\pi \epsilon_0}\dfrac{q}{r}$

$\dfrac{q}{V} = {4\pi \epsilon_0}{r}$

$C = \dfrac{1}{9\times 10^9}\times\dfrac{2.54\times 10^{-2}}{2}$

C = 0.1411 × 10⁻¹¹ Farad                      

C = 1.411 × 10⁻¹² Farad                

C = 1.4 pF                            

Hence, correct answer is option A