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 wiresif they are 70 cm long and 1.5 cm apart? Is the force attractive or repulsive?

The wires which connect the battery of an automobile to its starting m

1.	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 wiresif they are 70 cm long and 1.5 cm apart? Is the force attractive or repulsive?
Answer» Solution :`1.2 N m^(-1)` , repulsive. Note, obtaining TOTAL force on the wire as `1.2 x× 0.7 = 0.84 N` , is only APPROXIMATELY correct because the formula `F = (mu_0)/(2pi r) I_1 I_2`for force per UNIT LENGTH is strictly valid for infinitely LONG conductors.

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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 wiresif they are 70 cm long and 1.5 cm apart? Is the force attractive or repulsive?

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