Two light bulbs are in the circuit shown: Are the bulbs in parallel or series? _

ID: 1512725 • Letter: T

Question

Two light bulbs are in the circuit shown:

Are the bulbs in parallel or series? _____________

Calculate the current flowing through each bulb._____________ A

Calculate the voltage used by each bulb:

8? bulb: ___________V

4? bulb: _____________V

Which light bulb has the most current? _______________

Calculate the power used by each bulb:

8? bulb: __________W

4? bulb: ___________W

Brightness is about power. So which bulb is brighter? _____________

Calculate the power generated by the batteries. _____________W

1. The two bulbs are in series.

2. Current flowing through the bulbs I is = V(net voltage) / R(net resistance) = (3+3)/(8+4) = 0.5 A

3. voltage used by 8 ohm bulb : V1=IR = 0.5*8 = 4V

4. voltage used by 4 ohm bulb : V2=IR = 0.5*4 = 2V

5. both bulbs have the same current since they are in series

6. Power used by 8 ohm bulb P= IV1= 0.5*4 = 2W (voltage at 8 ohm is 4V from answer 3)

7. Power used by 4 ohm bulb P= IV2= 0.5*2 = 1W (voltage at 4 ohm is 2V from answer 4)

8. 8 ohm bulb is brighter

9. power generated by batteries is= Vsource * Current in circuit = 6*0.5 = 3W

which is also equals to dissipated power at resistors

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