Page 32 - CHAPTER-1 (Electricity)

CHAPTER 1

ELECTRICITY

V
V
V
Total current, I=I +I +I By Ohm’s law, I = R 1 , I = R 2 and I = R 3
1
1
2
3
3
2
V
If is the equivalent resistance, then I=
R
Thus,
V V V V V 1 1 1
=
R R 1 + R 2 + R 3 ⟹ R =V ( R 1 + R 2 + R 3 )

1 1 1 1
⟹ = + +
R R 1 R 2 R 3

Some important points regarding parallel combination of resistors

are as follows:

1. The reciprocal of equivalent resistance is equal to the sum of the

reciprocal of individual resistances.

2. The equivalent resistance is less than the resistance of either

resistor. This is also known as minimum effective resistance.

3. The current from the source is greater than the current through

either resistor.

4. The potential difference across each resistor is same.

Applications of Parallel Combination:

• The parallel combination of resistances is highly useful in

circuits used in daily life, as the circuits used have components

of different resistances requiring a different amount of current.

• This type of combination in a circuit will divide the current

among the components (electrical gadgets), so that they can

have the necessary amount of current to operate properly. This

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