New Current..?

Question

A resistor is placed in a circuit. The current in the circuit is 2 amperes and the voltage drop across the resistor is 8 volts. The voltage is then increased to 12 volts. What will be the new current?

 

Show all work please

 

Answer 1

Ohm's Law:

 

V = I*R  where:

• V = voltage in volts
• I = Current in amperes (amps)
• R = Resistance in ohms

 

Initially V = 8 volts and I = 2 amps.  Find the resistance, R:

 

     V = I*R

     8 volts = (2 amperes)*R

     (8 volts)/(2 amps) = R

     4 ohms = R

 

When the voltage is increased to 12 volts, we know R = 4 ohms.  Find the current I:

 

     V = I*R

     12 volts = I*(4 ohms)

     (12 volts)/(4 ohms) = I

     3 amps = I

Answer 2

By Ohm's law,

 

R = V/I = 8 volts / 2 amps = 4 ohms

 

At 12 volts,

 

I = V/R = 12 volts / 4 ohms = 3 amps