Question 491: Electrostats & Capacitance

Question

The two thin coaxial rings, each of radius 'a' and having charges +Q and $$-$$Q respectively are separated by a distance of 's'. The potential difference between the centres of the two rings is :

Accepted Answer

$${V_A} = {{KQ} \over a} - {{KQ} \over {\sqrt {{a^2} + {s^2}} }}$$
$${V_B} = {{ - KQ} \over a} + {{KQ} \over {\sqrt {{a^2} + {s^2}} }}$$
$${V_A} - {V_B} = {{2KQ} \over a} - {{2KQ} \over {\sqrt {{a^2} + {s^2}} }}$$
$$ = {Q \over {2\pi {\varepsilon _0}}}\left( {{1 \over a} - {1 \over {\sqrt {{s^2} + {a^2}} }}} \right)$$

Answer

$${Q \over {2\pi {\varepsilon _0}}}\left[ {{1 \over a} + {1 \over {\sqrt {{s^2} + {a^2}} }}} \right]$$

Answer

$${Q \over {4\pi {\varepsilon _0}}}\left[ {{1 \over a} + {1 \over {\sqrt {{s^2} + {a^2}} }}} \right]$$

Answer

$${Q \over {4\pi {\varepsilon _0}}}\left[ {{1 \over a} - {1 \over {\sqrt {{s^2} + {a^2}} }}} \right]$$

Answer

$${Q \over {2\pi {\varepsilon _0}}}\left[ {{1 \over a} - {1 \over {\sqrt {{s^2} + {a^2}} }}} \right]$$

Electrostats & Capacitance

The two thin coaxial rings, each of radius 'a' and having charges +Q and $-$Q respectively are separated by a distance of 's'. The potential difference between the centres of the two rings is :

Choose the correct answer: