Chapter 18 – D.C. Circuits

1.

Explain why electric lights in a building are connected in parallel rather than in series.

• When the bulbs are connected in parallel, the current through each bulb will be higher and hence each bulb will glow more brightly.

• Parallel arrangement also allows the bulbs to work independently. That is, when one bulb is fused or blown, the other bulbs can still work.

2. 

Resistor A and B are in parallel. Would the addition of an extra resistor parallel to A and B increase or decrease the current flowing through the battery? Explain your answer.

• Adding a resistor in parallel decreases the effective resistance of a circuit.

• Using I=V/R, the current through the battery will increases.