The Total solution for NCERT class 6-12
The wires which connect thebattery of an automobile to its starting motor carry a current of 300 A (for ashort time). What is the force per unit length between the wires if they are 70cm long and 1.5 cm apart? Is the force attractive or repulsive?
Current in both wires, I =300 A
Distance between the wires, r =1.5 cm = 0.015 m
Length of the two wires, l =70 cm = 0.7 m
Force between the two wires isgiven by the relation,
Where,
= Permeability of free space =
Since the direction of thecurrent in the wires is opposite, a repulsive force exists between them.