KCET2015PhysicsMagnetic Effects of Current
Two parallel wires ( 1 ~m ) apart carry currents of ( 1 ~A ) and ( 3 ~A ) respectively in opposite directions. The force per unit length acting between these two wires is
Options
- A( 6 10⁻⁷ Nm ⁻¹ ) repulsive
- B( 6 10⁻⁷ Nm ⁻¹ ) attractive
- C( 6 10⁻⁵ Nm ⁻¹ ) repulsive
- D( 6 10⁻⁵ Nm ⁻¹ ) attractive
Correct answer
A. ( 6 10⁻⁷ Nm ⁻¹ ) repulsive
Step-by-step solution
Consider the two parallel wires as shown in the following figure. Now, force experienced by the two wires is [ F= ₀ 4_ 2 I₁ I₂ d ] We know ( I₁=1 A ; I₂=3 A ; d=1 m ) and ( ₀ 4 =10⁻⁷ ) Therefore, ( F= 10⁻⁷ 2 1 3 1 =6 10⁻⁷ ) and since the currents are in opposite directions, therefore, force experienced will be repulsive So, the force per unit length acting between two wires is ( 6 10⁻⁷ ~N ~m ⁻¹ ) and it is repulsive.