Two long, parallel conductors carry currents in the same direction, as shown in figure. Conductors A held firmly in position. Conductors B carries a current `I_(B)` and is allowed to slide freely up and down (parallel to A) between a se of non-conducting guides. the mass per unit length of conductors B is 0.1 g/cm and the distance between the two conductors is 5 cm. if system of conductors is in equilibrium , the value of current `I_(B)` is

Options

A. 250 A
B. 240 A
C. 220 A
D. 230 A

Answer

a

Explanation

When system of conductors is in equilibrium. The magnetic force of attraction per unit length between conductors =weight of conductors B per unit length.
`(mu_(0))/(2pi) (l_(A)xxl_(B))/d=(mg)/L =(m/L)g`
`(mu_(0))/(2pi) (l_(A)xxl_(B))/d=(m/L)g`
`2xx10^(-7) xx(100xxl_(B))/0.05 =(0.01kg//m) xx10`