The wires which connect the battery of an automobile to its starting motor carry a current of 300 A (for a short time). What is the force per unit length between the wires if they are 70 cm long and 1.5 cm apart ? Is the force attractive or repulsive ?

Explanation

`F=(mu_(0))/(4pi)xx(2I_(1)I_(2))/(r )`
`=10^(-7)xx(2xx300xx300xx100)/(1.5xx10^(-2))=1.2 Nm^(-1)` (Repulsive force)