Question

Two parallel wires PQ and RS are connected by a capacitor and a metal rod CD and placed in a magnetic field directed into the page as shown in figure. If rod CD is moved with a velocity υ as shown in the figure,

• A. Plate 1 of the capacitor acquires a positive charge and plate 2 an equal negative charge
• B. plate 1 of the capacitor acquires a negative charge and plate 2 an equal positive charge
• C. plates 1 and 2 do not acquire any charge
• D. the energy stored in the capacitor increases linearly with time

Answer 1

The correct option is A Plate 1 of the capacitor acquires a positive charge and plate 2 an equal negative charge

As the rod CD moves to the right, from Fleming’s left hand rule, the free electrons in CD experience a force from C to D. Hence, the electrons move from C to D and, as a result, end C acquires a positive charge (due to loss of electrons) and end D acquires an equal negative charge (due to gain of electrons). Therefore, plate 1 acquires a positive charge and plate 2 acquires an equal negative charge.