Exam 8: Transients, D.C Circuit Analysis, and D.C Machines

Decide whether each of these statements is True (T) or False When a capacitor of 8μF, which has been charged to 12 V, is connected across a 1 MΩ resistor: (i) The circuit current is proportional to the rate of change of voltage across the capacitor. (ii) 8 s after the connection, the circuit current has dropped to half its initial value.

Decide whether each of these statements is True (T) or False A 24 V supply is connected to a series arrangement of a 100 Ω resistor and a 50 mH inductor. (i) The initial circuit current is 0.24 A. (ii) After a time equal to the time constant, the circuit current has decreased to 36.8% of its initial value.

Decide whether each of these statements is True (T) or False For a series wound d.c. motor: (i) The armature and field coils always carry the same current. (ii) The motor has a high starting torque.

The Thévenin equivalent circuit for the circuit to the left of the terminals X and Y in the following circuit is:

Decide whether each of these statements is True (T) or False For a shunt wound d.c. motor: (i) The armature and field coils always carry the same current. (ii) The motor has a high starting torque.

Decide whether each of these statements is True (T) or False With a d.c. generator, a split-ring commutator is used to: (i) Reverse the connections to the rotor winding every half-cycle. (ii) Via brushes give the output voltage.