1What is direct current? Name three of its sources.
2What is alternating current? How does a dynamo produce it?
3Describe the time current graph of direct current and of alternating current.
4What is frequency? What is its unit, and what does 1 Hz mean?
5The a.c. used in Nepal has a frequency of 50 Hz. What does this mean, and how many times does its direction change in one second?
6Why is the frequency of direct current zero?
7What is a rectifier? Give one everyday use of it.
8Name two appliances that run on a.c., two things that use d.c., and two appliances that can run on both.
9An a.c. generator completes 200 cycles in 4 seconds. What is its frequency, and how many times does its direction change each second?
10Give two arrangements people use during load shedding, and say which kind of current each gives.
11Why does a dynamo not have a fixed positive and negative terminal like a cell?