Ahair dryer draws 14.5 a when plugged into a 120-v line. assume direct current.

(a) What is its resistance? Express your answer to two significant figures and include the appropriate units."

(b) How much charge passes through it in 11 min ? Express your answer to two significant figures and include the appropriate units.

Solution

(a) We can calculate the resistance by using Ohm's law:

Since we know that  and , we can find R:

(b) The current is equal to the quantity of charge by unit of time:

In our problem, t=11min=660 s, so we can calculate the charge passed through the hair dryer:

measuring things 1 litre of water