## General Knowledge 203

Test # 203

1.
The Kaziranga National Park, which is known for its one-horned rhinos is located in ___________?

Login/Register to access massive collection of FREE questions and answers.

gk13
Quiz Index
2160 questions in 216 tests. Each test contains 10 questions.

Apples are actually part of the rose family.      .. More >>

n.
1.a clear oily poisonous liquid added to gasoline to prevent knocking      .. More >>

### Direct Current Versus Alternating Current

something called direct current DC. The positive and negative terminals of a battery are always, respectively, positive and negative. Current always flows in the same direction between those two terminals.

The power that comes from a power plant, on the other hand, is called alternating current AC. The direction of the current reverses, or alternates, 60 times per second in the U.S. or 50 times per second in Europe, for example. The power that is available at a wall socket in the United States is 120 volt, 60 cycle AC power.

The big advantage that alternating current provides for the power grid is the fact that it is relatively easy to change the voltage of the power, using a device called a transformer. Power companies save a great deal of money this way, using very high voltages to transmit power over long distances.

How does this work? Well, lets say that you have a power plant that can produce 1 million watts of power. One way to transmit that power would be to send 1 million amps at 1 volt. Another way to transmit it would be to send 1 amp at 1 million volts. Sending 1 amp requires only a thin wire, and not much of the power is lost to heat during transmission. Sending 1 million amps would require a huge wire.

So power companies convert alternating current to very high voltages for transmission such as 1 million volts, then drop it back down to lower voltages for distribution such as 1,000 volts, and finally down to 120 volts inside the house for safety. As you might imagine, its a lot harder to kill someone with 120 volts than with 1 million volts and most electrical deaths are prevented altogether today using GFCI outlets. To learn more, read How Power Grids Work.

Vocabulary Flashcards
• Must is a 'modal auxiliary verb'. There is no -s in the third person singular.
He must start corning on hive. (NOT He musts . . .)
Questions and negatives are made without do.
Must you go? (not Do you must go?)
You mustn't worry. (NOT You don't must worry.)
After must, we use the infinitive without to.
I must write to my mother. (NOT I must to write . . .)
• Must has no infinitive or participles. When necessary, we use other expressions, such as have to.
He II have to start coming on time. (NOT He'll must . . .)
i don't want to have to tell you again. (NOT I don't want to-must . . .)
• Must has no past tense: We can talk about past obligation with had to.
I had to push the car to start it this morning. (NOT I must push . . .) Must can have a past meaning in reported speech.
I told her she must be home by midnight.
• There is a contracted negative mustn't.
• .. Next ...