- #1

Sean1218

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## Homework Statement

The circuit shows a source of EMF and some identical light bulbs. The switch, S, is opened at some point. The questions refer to the situation before and after the opening of S. Answer true or false for each statement.

1. When S is opened, the potential difference across bulb 4 increases.

2. When S is opened, the current through bulb 2 decreases.

3. When S is closed, bulb 1 is brighter than bulb 4.

4. When S is closed, bulb 1 is brighter than bulb 2.

5. When S is opened, bulb 4 becomes brighter.

Circuit: http://i.imgur.com/E9e5Y.gif

## Homework Equations

V=IR

P=I

^{2}R

## The Attempt at a Solution

I answered the following:

1. False

2. True

3. False

4. False

5. False

I figured that voltage is constant from the battery, and voltage is the same for each bulb in a parallel circuit, so #1 is False.

Taking away bulb 3 from the circuit means more current for bulb 2 and 3, but it also increases the resistance in the parallel circuit (and thus the total resistance), so the current decreases to compensate. Not sure what the answer would be for #2.

#3 and #4 are the same question as far as I can tell, since bulb 2 and bulb 4 should be identical. I just messed with ratios for the last 3 questions, but I'm not really sure about these.

Any help?