,ALTERNATING
CURRENT
, QUIZRR 3
1. Alternating Current
As the name suggests, alternating current (ac) is current that flows in one direction in a conduc-
tor, then changes direction and flows in the other direction.
The reason for this alternation is the way current comes from the electric generators. The emf and
current produced by the generator does not alternate instantly between maximum values in each
direction, but they build up to maximum values and then decrease, change dierction and build
to maximum values in the other direction.
I Conductor I (d)
(a)
+
(a)
(b)
I=0
t
(b)
I
(c)
–
I (c)
(d)
Whereas, the direct current can be shown as below.
emf E
Current I
t
If the current or voltage varies periodically as ÂsinÊ or ÂcosÊ function of time, the current or voltage
is said to be sinusoidal.
+
+ +
I = I0 sin t
I or V t
V = V0 sin t
·
·
ALTERNATING CURRENT
CURRENT
, QUIZRR 3
1. Alternating Current
As the name suggests, alternating current (ac) is current that flows in one direction in a conduc-
tor, then changes direction and flows in the other direction.
The reason for this alternation is the way current comes from the electric generators. The emf and
current produced by the generator does not alternate instantly between maximum values in each
direction, but they build up to maximum values and then decrease, change dierction and build
to maximum values in the other direction.
I Conductor I (d)
(a)
+
(a)
(b)
I=0
t
(b)
I
(c)
–
I (c)
(d)
Whereas, the direct current can be shown as below.
emf E
Current I
t
If the current or voltage varies periodically as ÂsinÊ or ÂcosÊ function of time, the current or voltage
is said to be sinusoidal.
+
+ +
I = I0 sin t
I or V t
V = V0 sin t
·
·
ALTERNATING CURRENT
