Question

Find the formulae of equivalent resistance of the resistances in parallel combination with the help of a diagram.

Answer 1

Heya........!!!

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Consider 3 resistors in parallel ( R1 ,R2 and R3 . )

Total current ( I )

• Current in 3 branches = I1 , I2 and I3
• Total voltage = V

=> I = I1 + I2 + I3

=> I1 = V / R1
=> I2 = V /R2
=> I3 = V / R3

I1 + I2 + I3 = V / R1 + V / R2 + V / R3

Let equivalent resistance be ( Re )

=> Re = V / I => I = V / Re

=> V / Re = V/ R1 + V / R2 + V / R3

♦ => 1 / Re = 1 / R1 + 1 / R2 + 1 / R3

=> In parallel combination the equivalent resistance is the sum of reciprocal of the individual resistance i.e 1 / R1 + 1 / R2 + 1 / R3...... and so on .

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