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SMJK CHUNG HWA, KOTA BHARU
Chapter 23 (1) Alternating Current In Pure Resistor
1. An alternating current I is represented by the following equation:
I = (2.0 A)sin(100t)
Where time t is measured in second.
Determine,
a) The maximum current.
b) The frequency of oscillation of the current.
c) The current at time
i) t = 2.5 ms
ii) t = 12.5 ms
Ans : a) 2.0 A
b) 50 Hz
c) i) 1.41 A
ii) -1.41 A
2. A current I is represented by the following equation:
I = (4 A)sin(100t)
Where time t is measured in second.
Determine,
a) The current at time t =
1
T.
12
b) The time when the current has a value of +3.46 A.
Ana : a) 2 A
b) 3.33 X 10-3 s
3. The voltage V applied across a circuit element is given by
V = (20 V)(sin(100t)
The current flowing through the element is given by
I = (2 A)sin(100t)
Determine the electrical power delivered to the element at time t = 2.0 ms.
Ans : 13.8 W
4. A alternating voltage V is given by
V = (12 V)(sin(120t)
It is applied across a 10  resistor.
Determine,
a) The average electrical power supplied to the resistor.
b) The amount of heat produced by the resistor in 2 minutes.
Ans : a) 7.2 W
b) 864 J
5. A current I which is given by
I = (20 A)(sin(100t)
flow through a 20  resistor. Determine,
a) The maximum voltage that can be applied across the resistor.
b) The amount of heat produced by the resistor.
Ans : a) 400 V
b) 2.40 X 106 J