Parallel Circuits - Technical MCQs

Q1:

If R1 opens in the given circuit, the total current equals ___.

A 86 mA

B 170 mA

C 42 mA

D 128 mA

ANS:A - 86 mA

The 170 mA is a result of the equivalent resistance of the two parallel resistors. Therefore, if you remove the Resistor R1 then the total current would just be the current flowing through R2 since it is the only resistor left.

IT = (Vs)/(R1||R2) = 170ma,
If R1 is open then,
IT = (Vs)/(R2) = 128ma.