SAMPLE QUESTIONS
1. A copper rod is bent into a semi-circle of radius a and at ends straight parts are bent along diameter of the semi-circle and are passed through fixed, smooth and conducting ring O and O' as shown in figure. A capacitor having capacitance C is connected to the rings. The system is located in a uniform magnetic field of induction B such that axis of rotation OO' is perpendicular to the field direction. At initial moment of time (t = 0), plane of semi-circle was normal to the field direction and the semi-circle is set in rotation with constant angular velocity ω. Neglect the resistance and inductance of the circuit. The current flowing through the circuit as function of time is
a) $\frac{1}{4}\pi \omega ^{2}a^{2}CB\, cos\omega t$
b) $\frac{1}{2}\pi \omega ^{2}a^{2}CB\, cos\omega t$
c) $\frac{1}{4}\pi \omega^{2}a^{2}CB, sin\omega t$
d) $\frac{1}{2}\pi \omega ^{2}a^{2}CB\, sin\omega t$
2. The energy stored in an inductor is
a) Electrostatic
b) Electromagnetic
c) Magnetic
d) Mechanical