Consider three long straight parallel wires as shown in the figure. Length of wire B is 25 cm. Choose the correct options.

(A) Net force experienced by wire B is $2 × 10^{-4} N$ towards left
(B) Magnitude of repulsion force by wire A on B is $5 × 10^{-4} N$
(C) Magnitude of repulsion force by wire C on B is $2 × 10^{-4} N$
(D) Net force experienced by wire B is $2 × 10^{-4} N$ towards right

Choose the correct answer from the options given below:

(B) and (C) only

The correct answer is Option (2) → (B) and (C) only

Given: Currents: A = 30 A (up), B = 10 A (down), C = 20 A (up). Distances: AB = 3 cm, BC = 5 cm, length of B = 25 cm.

Force between two parallel currents (magnitude): $F = \frac{μ_0 I_1 I_2 L}{2π d}$ with $ \frac{μ_0}{2π} = 2\times10^{-7}\,$N·A⁻2·m⁻1.

Force on B due to A (repulsive, pushes B to the right):

$F_{BA}=2\times10^{-7}\times\frac{30\times10\times0.25}{0.03}=5.0\times10^{-4}\ \text{N}$

Force on B due to C (repulsive, pushes B to the left):

$F_{BC}=2\times10^{-7}\times\frac{20\times10\times0.25}{0.05}=2.0\times10^{-4}\ \text{N}$

Net force on B (rightward):

$F_{net}=F_{BA}-F_{BC}=5.0\times10^{-4}-2.0\times10^{-4}=3.0\times10^{-4}\ \text{N}$ (towards right).

Therefore correct options: (B) and (C)