4.1The current through a branch in a linear network is 2 A when the input source voltage is 10 V. If the voltage is reduced to 1 V and the polarity is reversed, the current through the branch is:

(b) −0.2

4.2For superposition, it is not required that only one independent source be considered at a time; any number of independent sources may be considered simultaneously.

(a) True

4.3The superposition principle applies to power calculation.

(b) False

4.4Refer to Fig. 4.67. The Thevenin resistance at terminals a and b is:

(d) 4Ω

4.5The Thevenin voltage across terminals a and b of the circuit in Fig. 4.67 is:

(b) 40 V

4.6The Norton current at terminals a and b of the circuit in Fig. 4.67 is:

(a) 10 A

4.7The Norton resistance RN is exactly equal to the Thevenin resistance RTh.

(a) True

4.8Which pair of circuits in Fig. 4.68 are equivalent?

(c) a and c

4.9A load is connected to a network. At the terminals to which the load is connected, RTh = 10 Ohmand VTh = 40 V. The maximum power supplied to the load is:

(c) 40 W

4.10The source is supplying the maximum power to the load when the load resistance equals the source resistance.

7.1An RC circuit has R = 2 Ωand C = 4 F. The time constant is:

(d) 8 s

7.2The time constant for an RL circuit with R = 2 Ωand L = 4 H is:

(b) 2 s

7.3A capacitor in an RC circuit with R = 2 Ω and C = 4 F is being charged. The time required for the capacitor voltage to reach 63.2 percent of its steady-state value is:

(c) 8 s

7.4An RL circuit has R = 2 Ω and L = 4 H. The time needed for the inductor current to reach 40 percent of its steady-state value is:

(b) 1 s

7.5In the circuit of Fig. 7.79, the capacitor voltage just before t = 0 is:

(d) 4 V

7.6In the circuit of Fig. 7.79, v(∞) is:

(a) 10 V

7.7For the circuit of Fig. 7.80, the inductor current just before t = 0 is:

(c) 4 A

7.8In the circuit of Fig. 7.80, i(∞) is:

(e) 0 A

7.9If vs changes from 2 V to 4 V at t = 0, we may express vs as:

(c) 2u(−t) + 4u(t) V

(d) 2 + 2u(t) V

7.10The pulse in Fig. 7.110(a) can be expressed in terms of singularity functions as: