Posted by Nilan on .
Resistors of 30 ohms and 60 ohms are connected in parallel and joined in series to a 10 ohm resistor.
The circuit voltage is 180 volts.
Find:
the voltage of the parallel circuit
the voltage across the parallel circuit
the current through the 10 ohm resistor

physics  need help 
drwls,
The two parallel resistors behave like a single serives resistor of equivalent resistance Req
1/Req = 1/30 + 1/60 = 1/20
So Req = 20 ohms
The total circuit current is
V/R = 180/(20 + 10) = 6 Amps
The voltage drop is 60 V across the 10 ohm resistor and 120 V across the pair of parallel resistors. You seem to be asking the same question twice.
All of the circuit current (6A) goes through the 10 ohm resistor