If you have a 90 V power source with a 30-Ω and 60-Ω resistor in series, what is the voltage drop over the 60-Ω resistor?

30 V

2 V

60 V

90 V

= 60 V

Explanation:

Total resistance = 30 Ω + 60 Ω

= 90 Ω

Voltage = 90 V

We can calculate current through the circuit.

I = V/R

= 90 v/90Ω

= 1 A

Since the resistors are in series arrangement, then the current through both resistors are the same.

Current through 60Ω resistor is 1 A

Therefore; V = IR

= 1 A * 60 Ω

= 60 V

Therefore; the voltage drop over the 60-Ω resistor is 60 V