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Parallel Circuits - Technical MCQs

Q1:

What happens to total resistance in a circuit with parallel resistors if one of them opens?

A It increases.

B It halves.

C It remains the same.

D It decreases.

ANS:A - It increases.

Consider r1 ,r2 are the resistance which are in parallel.

If any one of resistor get open mean the connection became series.

Ex:

r1 = 2kohm.
r2 = 1kohm.

If both are in parallel means Rt = r1*r2/(r1+r2) = 2/3 = 0.667 kohm.

If both are in series means,

Rt = r1+r2.
Rt = 2+1 = 3kohm.

So resistance value increases when one of them get opened.