202 Transient analysis5 Define a step voltage.
6 Give the symbol for and the unit of time constant.
7 Give an expression for the time constant of an RL circuit.
8 A coil has an inductance of 10 mH and a resistance of 5 1). If a step
voltage of 10 V is applied to the coil, how long will it take for the current
to reach its final steady state value?
9 What ~,-, the initial rate of rise of the current in the coil in Question 8?10 What is the final steady state value of the current in the coil of Question 8?
11 State the form of the voltage across the capacitor in a series RC circuit to
which a step voltage is applied.
12 State the form of the current in the circuit of Question 11.
13 A series RL circuit is to be used as an integrator. Across which circuit
element should the output voltage be taken?
14 A series RC circuit is to be used as a differentiator. Across which circuit
element should the output voltage be taken?
15 What is the value of the time constant of an RC series circuit having
R = 5 k~ and C = 0.1 ~F?
16 A 10 ~F capacitor, charged to 100 V is discharged through a resistance of
100 ~. How long will it take to become fully discharged.
17 What will be the current in the circuit of Question 16 after a time equal to
the time constant of the circuit?
18 An RC circuit having a time constant of 10 ~zs is connected to a 100 V d.c.
supply. If it is partially charged to 50 V and then immediately discharged
through the resistance, how long will it take to become fully discharged?
19 What is the advantage of using Laplace transforms in the analysis of the
transient operation of electric circuits?
20 What is a transform circuit?
8.6 PROBLEMS
1 A step voltage of amplitude 100 V is applied to a coil of inductance 10 H
and resistance 10 1~. Determine (a) the initial rate of rise of current in the
coil in ampere per second, (b) the value of the current after 0.1 s, (c) the
circuit time constant, (d) the final steady state value of the current and (e)
the time taken for the current to reach its steady state value.