46

10 V

V1₁-01|||

20 V

4 At

R6

R4

+

116 V

V3-6V

V4-12 V

R₂

Figure P1.26: Circuit for Problem 1.26.

+6V- 1A 2A

2

+1A

+

10 V 3

V₂-4V

1.27 For each of the eight devices in the circuit of Fig. P1.27,

determine whether the device is a supplier or a recipient of

power and how much power it is supplying or receiving.

R₂

+8V-

+4V-

6

+12 V-

R₁

-7V +

Figure P1.27: Circuit for Problem 1.27.

3A

9 V

+

1.28 For each of the seven devices in the circuit of Fig. P1.28,

determine whether the device is a supplier or a recipient of

power and how much power it is supplying or receiving.

*1.29 An electric oven operates at 120 V. If its power rating is

0.6 kW, what amount of current does it draw, and how much

energy does it consume in 12 minutes of operation?

1.30 A 9 V flashlight battery has a rating of 1.8 kWh. If

the bulb draws a current of 100 mA when lit; determine the

following:

SA

+

24 V 1

CHAPTER 1 CIRCUIT TERMINOLOGY

+6V-

2

1A,

3 A

8

V

3.

2 A

+4V-

Figure P1.28: Circuit for Problem 1.28.

12 V

X

4 A

(b) How much energy in joules is contained in the battery?

(e) What is the battery's rating in ampere-hours?

1.31 The voltage across and current through a certain device

are given by

u(t) = 5 cos(4x1) V,

i(t) = 0.1 cos(4x1) A.

Determine:

*(a) The instantaneous power p(t) at t = 0 and r = 0.25 s.

(b) The average power Pav, defined as the average value of

p(t) over a full time period of the cosine function (0 to

0.5 s).

1.32 The voltage across and current through a certain device

are given by

u(t) = 100(1-e-0.21) V.

i(t) = 30e-0.2¹ mA.

Determine:

(a) The instantaneous power p(1) at 1 = 0 and r = 3 s.

(b) The cumulative energy delivered to the device from t = 0

to / = 00.

1.33 The voltage across a device and the current through it

are shown graphically in Fig. P1.33. Sketch the corresponding

power delivered to the device and calculate the energy absorbed

by it.

1.34 The voltage across a device and the current through it

are shown graphically in Fig. P1.34. Sketch the corresponding

power delivered to the device and calculate the energy absorbed