Day 22

Professor Mason uses a demo to show us how AC power works. 

When professor Mason used AC power and DC power to light the bulb at the same voltage. We saw the AC one is dimmer. It showed that the bulb has less power with AC. 

When professor Mason increased voltage for AC above 1.4 times of the DC power, the bright went to the same high. 

Vrms = 1/sqrt(2) Vmax. 

When we read voltage Vmax, it instead of Vrms. So the power of AC is P=Vrms^2/R. 

summary
Today, we reviewed that the relationship between Vrms and Vmax, and proved how to calculate the power about AC.