Experiment: With the battery voltage set to 20 volts, measure the current in a parallel circuit with 1, 2, 3, and 4 light bulbs. (In each case, place the ammeter next to the battery.) Use Ohm’s law to calculate the total resistance of the circuit. Record results below.

Question

Number of light bulbs
1
2
3
4
Voltage
20 volts
20 volts
20 volts
20 volts
Current
1.33 A
1.33 Amps
0.44 Amps
0.27 Amps
Total resistance(show all work)

Answer 1

Number of light bulbs: 1

Total resistance = Voltage / Current
Total resistance = 20 volts / 1.33 A
Total resistance = 15.04 ohms

Number of light bulbs: 2

Total resistance = Voltage / Current
Total resistance = 20 volts / 1.33 A
Total resistance = 15.04 ohms

Number of light bulbs: 3

Total resistance = Voltage / Current
Total resistance = 20 volts / 0.44 A
Total resistance = 45.45 ohms

Number of light bulbs: 4

Total resistance = Voltage / Current
Total resistance = 20 volts / 0.27 A
Total resistance = 74.07 ohms