Page 45 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

Fig 16

Current in parallel circuit (Fig 17)
Current in resistor R =I =V /R 1
1
1
1
Current in R =I =V /R 2
2 2 2
Current in R =I =V /R 3
3
3
3
Total current I in the parallel circuit is the sum of the individual branch current i.e. I =I +I +I 3
2
1
Fig 17

Resistance in parallel circuit (Fig 18)
We have also seen I = I +I +I or
3
2
1
V/R=V/R +V/R +V/R ,
1 2 3
Therefore1/R=1/R +1/R +1/R 3
2
1
The above equation reveals that in parallel a circuit, the reciprocal of the total resistance is equal to the sum of
the reciprocal of the individual branch resistance. By the application of ohm’s law we can write R = V/I ohms, I =
V/R amps
Fig 18

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CITS : Power - Electrician & Wireman - Lesson 5 - 12