Question

A series circuit has two 5.0-ohm resistors and a power source of 9.0 volts. How will the current be affected and what will it be if another resistor (with a resistance of 7.5 ohms) is added to the circuit?
A.increase; 0.51 amps
B.increase; 0.72 amps
C.increase; 3.6 amps
D.decrease; 0.51 amps
E.decrease; 0.72 amps

Answer 1

The formula for solving current given with resistance and power source or voltage is shown below:
I = V/R  

When two 5 ohms resistors are in series, we have:
I = 9 volts / (5+5 ohms)
I = 0.9 amperes

When it is being added with another 7.5 resistors, we have:
I = 9 volts / (5+5+7.5 ohms)
I = 0.529 ampere

The answer to the question is the letter "D. decrease; 0.51 amps".