Question

1) What happens to the electrical flow going into and out of the battery if you add more bulbs in parallel? 2) What happens to the electrical flow going into and out of the battery if you add more bulbs in series? 3) Let's say you have three bulbs (bulb 1, bulb 2 and bulb 3) in parallel and you create "short" pathway across bulb 3, what happens to the brightness of the bulbs? 4) What happens to the brightness of each bulb if you switch the positions of the bulbs in circuit 11 on page 3-5 lab handout? 5) What happens if you unscrew the 3.8 V bulb in circuit 11 on page 3-5 of the lab handout? 6) What happens to the brightness of the 3.8 V bulb if you unscrew the 1.5 V bulb in circuit 12 on page 3-8 of the lab handout? 1.5 V 3.8 V Circuit 11 Circuit 12

Answer 1

(1) Adding more bulbs in parallel will effectively reduce the equivalent resistance of the circuit, and hence current will increase according to Ohm's Law. Hence, the elctrical flow going out and in the battery will increase.

(2) Adding more bulbs in series will effectively raise the equivalent resistance of the circuit, and hence current will decrease according to Ohm's Law. Hence, the elctrical flow going out and in the battery will decrease.

(3) Creating a short path across any one bulb will create a shotcut to pass electric current, instead of passing through any of the bulbs, since they all will be ( 3 bulbs + short ) in parallel then. Hence, brightness of all bulbs will reduce.

(4) Brightness will not change upon switching the positions of the bulbs, since, current passing through the bulbs will remain same.

(5) Unscrewing one bulb will increase the potential difference across the other one, since, they are in series. Hence, current, and hence brightness of the connected bulb will increase.

(6) Unscrewing one bulb will not change the potential difference across the other one, since, they are in parallel. However, the effective resistance of the circuit will increase, hence, current going out and in the battery will decrease, but brightness of the conected bulb will remain unchanged.