Consider the situation shown in the figure. The wires PQ & RS are made to slide on the rails with the same speed 5 cm/s. Find the electric current in the 19 $\Omega$ resistor if (a) if both wires move towards right and (b) if PQ moves towards left but RS moves towards right.

Dear Student , 
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(a) When both wires move in same direction:
The sliding wires constitute two parallel sources of emf.
The net emf is given by
e = Blv
⇒ e = (1 × 4 × 10⁻² ) × 5 × (10⁻²)
       = 20 × 10⁻⁴ V
The resistance of the sliding wires is 2 Ω.
∴ Net resistance = $\frac{2\times 2}{2+2}$ + 19 = 20 Ω
Net current through 19 Ω = $\frac{2\times {10}^{-4}}{20}$ = 0.1 mA

(b) When both wires move in opposite directions with the same speed, the direction of the emf induced in both of them is opposite. Thus, the net emf is zero.

∴ Net current through 19 Ω = 0
Regards