ELECTRIC CURRENT

The famous French scientist Ampere, after whom the unit of current was named,

determined the difference between the current and static charges. Ampere gave the current direction: he supposed the current to flow from the positive pole of the source round the circuit and back again to the negative pole. The current which flows along wires consists of moving electrons. We know that the electron is a minute particle having an electric charge. As these charges travel along the wire, that wire is said to carry electric current. The electric current can flow through liquids and gases as well.

When the electrons flow in one direction only, the current is known to be DC, that is,

direct current. The simplest source of power for direct current is a battery, the battery pushes

the electrons in the same direction ( from the negatively charged terminal to the positively charged terminal ).The letters AC stand for alternating current. The AC flows first in one direction and then in the opposite one. The AC used for power and lighting purposes is assumed to go through 50 cycles in a second .One of the advantages of AC is the ease with which power at low voltage can be changed when it is necessary for long-distance transmission. The 90 % of electric energy to be generated now is AC. It finds application in lighting and heating. Russian scientist and inventor Yablochkov was the first to apply AC in practice.

O. Match the parts of sentences from two columns to form the completed sentences.

1.The electric current is 1. the energy of position

2. Kinetic energy is 2. electricity in rest

3. Static electricity is 3. the flow of moving electrons

4. Potential energy is 4. the energy of motion

5. The direct current is 5. a discharge

6. The lighting is 6. the flow of electrons in one direction

P. Ask your group-mates the following questions according this example:

For example: if electricity is a form of energy – Is electricity a form of energy?

1. if there are two types of electricity

2. if alternating voltage can be increased and decreased

3. if Franklin made the important contribution to the science of electricity

4. if Ampere determined the difference between the current and the static charges

5. if the electric current can flow through liquids and gases

6. if the electrolytes charge greatly when the current passes through them

7. if a negatively charged electron will move to the positive end of the wire

Q. Find the wrong statements and correct them.

1. Electrons flow from the positively charged terminal of the battery to the negatively

charged terminal.

1. Ampere supposed the current to flow from the negative pole to the positive one.
2. Static electricity is used for practical purposes.
3. Galvani thought that electricity was generated because of the contact of two dissimilar metals.
4. Static electricity is not very high in voltage and it is easy to control it.
5. Volta was very interested in atmospheric electricity and began to carry on

the experiments.

1. The direct current is known to flow first in one direction and then in the opposite one.
2. The direct current used for power and lighting purposes is assumed to go through 50 cycles a second.
3. Petrov was the first scientist who applied AC in practice.

R. Make the reports about the famous scientists and inventors : Thomas Edison, Volta,

Franklin, Galvani, Yablochkov or any other you wish.

Date: 2015-01-12; view: 2370