EEU 104: TUTORIAL 1 (2020/2021)
1. Determine the current flowing through an element if the charge flow is given by
(a) qt   3t  8 mC
(b) qt   ( 8t 2  4t-2) C
2.
The charge entering a certain element is shown in Fig. 1. Find the current at:
(a) t = 1 ms
(b) t = 6 ms
(c) t = 10 ms
Fig 1
3.
The voltage v across a device and the current I through it are
v t   5 cos 2t V,
i t   101  e 0.5t  A
Calculate:
(a) the total charge in the device at t = 1 s
(b) the power consumed by the device at t = 1 s.
4.
Calculate the power absorbed or supplied by each element in Fig. 2
Fig 2
5.
A 1.8‐kW electric heater takes 15 min to boil a quantity of water. If this is done once a day
and power costs 10 cents per kWh, what is the cost of its operation for 30 days?
6. A telephone wire has a current of 20  A flowing through it. How long does it take for a charge of
15 C to pass through the wire?
7. A bar of silicon is 4 cm long with a circular cross section. If the resistance of the bar is 240  at
room temperature, what is the cross‐sectional radius of the bar?
8. Determine Vo in the circuit in Fig. 3.
6
2

+
9V
+
+
Vo
3V

Fig 3
9.
From the circuit in Fig. 4, find I, the power dissipated by the resistor, and the power absorbed
by each source.
Fig. 4
10.
Find Vx in the circuit of Fig. 5.
2 Vx
1
+ –
15 V
+
5
2
Fig 5
+
Vx
11.
Calculate Vo in the circuit of Fig. 6.
4
+ Vo ‐
16 V
+
6
Fig 6
12.
Calculate Vo and Io in the circuit of Fig. 7.
Fig. 7
13. All resistors in Fig. 8 are 1  each. Find Req.
Req
Fig 8
14. Using series/parallel resistance combination, find the equivalent resistance seen by the source in
the circuit of Fig. 9. Find the overall dissipated power.
Fig 9
15. If Req = 50  in the circuit in Fig. 10, find R.
Fig 10
16. Find I in the circuit of Fig. 11
Fig 11
17. The lightbulb in Fig. 12 is rated 120 V, 0.75 A. Calculate Vs to make the lightbulb operate at the
rated conditions.
Fig 12
18. Figure 13 represents a model of a solar photovoltaic panel. Given that vs = 30 V, R1 = 20 , IL = 1
A, find RL.
R1
iL
Vs +
−
RL
Figure 13