The circuit below shows two identical lamps and 4 closed switches. The options b

Question

The circuit below shows two identical lamps and 4 closed switches. The options below identify a switch which is opened and a lamp which is being observed. Select the option that describes the behavior of the lamp when the switch is opened.

1. Brighter Stays Same Dimmer Goes Completely Out  What happens to lamp A when switch F is opened?
2. Brighter Stays Same Dimmer Goes Completely Out  What happens to lamp B when switch D is opened?
3. Brighter Stays Same Dimmer Goes Completely Out  What happens to lamp B when switch C is opened?
4. Brighter Stays Same Dimmer Goes Completely Out  What happens to lamp A when switch C is opened?
5. Brighter Stays Same Dimmer Goes Completely Out  What happens to lamp B when switch F is opened?
6. Brighter Stays Same Dimmer Goes Completely Out  What happens to lamp A when switch D is opened?

Explanation / Answer

Answer: The answer by kkappa is correct for a general case. But since you mentioned it incorrect, we can consider some special cases.

Special case 1: The bulbs are running at their maximum intensity so any increase in current shall not increase the brightness. Then the answers would be:

1.Lamp A goes off.

2.Lamp B goes off.

3.Lamp B goes off.

4. Lamp A goes off.

5. Lamp B stays same.

6. Lamp A stays same.

Special case 2: The bulbs are running at their maximum current readings when all switches are closed. So any increase in current could result in damage of the bulb (melting of the filament). Then the answers would be:

1.Lamp A goes off.

2.Lamp B goes off.

3.Lamp B goes off.

4. Lamp A goes off.

5. Lamp B goes off.

6. Lamp A goes off.

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