What happens to the brightness of bulbs in a series circuit as more bulbs are added and why?
1) The brightness of the bulbs increases because the current flowing through each bulb decreases.
2) The brightness of the bulbs decreases because the current flowing through each bulb increases.
3) The brightness of the bulbs remains the same because the current flowing through each bulb remains constant.
4) The brightness of the bulbs fluctuates randomly as more bulbs are added.