1. An incandescent light bulb, rated at 75W, is placed at one end of a 1.0m stick; at the other end of the meter stick we place an LED bulb that is rated at 9W. Upon measuring the voltage across each light bulb and the current through each lightbulb we find that the incandescent light bulb uses only 73W and the LED uses only 8.8W.

The two bulbs appear approximately equally bright. However, to investigate if both light bulbs are indeed equally bright we place a grease spot photometer (Fettfleckphotometer) between the two light bulbs. If the grease spot disappears against its surrounding when the photometer is precisely in the middle, i.e., when it is 50cm from each light bulb then the two light bulbs are indeed equally bright. However, in contrast to our anticipation, it turns out that the grease spot disappears against its surrounding when the photometer is 45cm from the incandescent bulb and 55cm from the LED bulb.

a) By what factor would the power of the dimmer of the two bulbs have to be increased, such that both light bulbs would be equally bright? (Such an increase can be accomplished, for example, with a Variac, which is a variable transformer.

b) What is the actual power that each of the two bulbs consume now?

c)In this case, where both bulbs produce the same amount of light, how much more power does the incandescent bulb consume compared to the LED bulb?