Basic Electricity
23
The current I will flow through 7 ohms resistor also.
The power absorbed by it will be
(6
2
) (7) = 252 W
(Ans).
Referring to Fig. 23-B and applying the current
division technique of equation (1.29).
1
2
1
2
I(R )
6
4
I
1.5 A
R
R
4
12
×
=
=
=
+
+
Current in 7 ohm resistor = current in 5
Ω
resistor
= I
2
, as they are in series
∴
Power absorbed by 7
Ω
resistor = (1.5
2
) 7
=
15.75 W (Ans).
Power absorbed by 5
Ω
resistor = (1.5)
2
× 5
= 11.25 W
(Ans).
Illustration 19
Three resistors of 2, 5 and 10
Ω
are joined in parallel
and a total current of 24 A is passed through them.
Find the current through each resistor.
Solution
The problem is dipicted in Fig. 1.24.
Fig. 1.23.
60 V
7
?
3
?
Fig. 1.23B. Circuit for illustration 18 with current
directions marked, for evaluation of I
2
The current I hence is, 60/10 = 6 A
The power delivered by the source is the product of
its V and I. That is 60 × 6 = 360 W
(Ans).
Fig. 1.24. Circuit for illustration 19
2
?
5
?
10
?
24 A
1
?
60 V
60 V
7
?
7
?
5
?
5
?
7
?
7
?
6
?
R
1
12
?
4
?
I
I
I
1
I
1
I
2
I
2
III
R
2
Fig. 1.23A.