Page 198 - WCS - Electrical

24
ohms = 2.4 ohms
Therefore R 
10

Example
Two resistors of 2 and 4 ohms are switched in parallel
to a 6V battery
– Calculate the total resistance WORKSHOP CALCULATION & SCIENCE - CITS
– Find the total current and partial current.

• The total resistance of a parallel connection is always Solution
smaller than the smallest resistance in the circuit. Solution
Total resistance
• In parallel connection the reciprocal of the total Total resistance
resistance is equal to the sum of the reciprocals of all
resistances in the circuit. 1 = 1 + 1
R R R
l = l + l + ... tot 1 2
1 2 1 1 2 + 1
V = V = V ... = 2 + 4 = 4
2
1
1 1 1 3 Ω
..........

  =

R R R 4
1 2 4 1
R = = 1 Ω
Example tot 3 3
Two resistances of 4 ohms and 6 ohms are connected in I Total = I + I current
parallel. Determine the total resistance. 1 2
U 6V
1
1   But I 1 = R 1 = 2Ω = 3A
1


R R R (since parallel connection)
1 2 I 2 = R U = 6V = 1.5A
4Ω
1 1 1 10 2



1.5A
Therefore  I total 3A = +
R 4 6 24
4.5= Amp
Assignment
Assignment 1 R = 12 ohms
1
R = 22 ohms
2
1 R = 12 ohms 3 V = 220 v R = 24 ohms in series
1
R = 22 ohms R = 40 ohms 3
1
2
R = 24 ohms in series V = 100 v R = ______ ohms
1
3
R = ______ ohms (in series) R 2
= ______ ohms 2 R = 15 ohms
1
2 R = 15 ohms R = 25 ohms
2
1 4 V = 80 v
R = 25 ohms V = 220 v
2
V = 220 v I = 2 A V = ______ v
1
V = ______ v R = 30 ohms V = ______ v
1
1
V = ______ v (in series) 2
R = ______ ohms
2
2
3 V = 220 v
R = 40 ohms
1
V = 100 v
1
Workshop Calculation & Science : (NSQF) Exercise 1.7.34 105 (in series) R
2
= ______ ohms
185
CITS : WCS - Electrical - Exercise 18