Lights dim when refrigerator is on

[gillgill]

1. In older houses, when a refrigerator starts up, the lights may dim briefly. When an electric heater is turned on, the lights may stay dimmed as long as it is on. Explain the difference.

2. Explain what is meant by the statement "a motor acts as a motor and generator at the same time." Can the same be said for a generator?

thanks

 

[Andrew Mason]

1. In older houses, when a refrigerator starts up, the lights may dim briefly. When an electric heater is turned on, the lights may stay dimmed as long as it is on. Explain the difference.

This question relates to the electrical load in a) starting up a motor compared to b) maintaining a constant heavy current through a resistance. It seems to be asking: why does the motor in the fridge draw more power when starting up and much less power afterward?

2. Explain what is meant by the statement "a motor acts as a motor and generator at the same time." Can the same be said for a generator?

A generator transfers kinetic energy into electrical energy by 'induction'. Does the motor, which turns electrical energy into kinetic energy by 'induction', also transfer some of that kinetic energy back into electrical energy? How? I think that is what the question asks.

As for the second part, does a generator produce electrical forces that try to stop or reduce the applied kinetic or turning forces?

AM

 

[gillgill]

ok...can u explain why?