1. Answer the following questions.

1. What forms of energy do you know?

2. Why electricity is the most important form of energy in modern technologies and everyday life?

3. What are the common sources of electric current?

4. What types of electric current do you know? What is the difference between them?

5. What units of measurement of electric quantities do you know?

6. What measuring devices do you know? What are they used for?

2. Change the Active to the Passive.

Example: The potential moves the particle.  The particle is moved by the potential.

The potential moves the particles.

The potential is moving the particle.

The potential has moved the particle.

The potential has been moving the particle.

The potential moved the particle.

The potential was moving the particle.

The potential had moved the particle.

The potential is going to move the particle.

3. Fill the blanks with a verb from the box using its Past Participle (-ed, 3 f.) form. Use each verb only once.

give, detect, measure, think, base, send, employ

The presence of an electric current in a circuit may be _______ and its strength may be _________ by a number of different methods, each method being ________ upon some effect which the current produces under given conditions.

These programs are useful because they can be ______ to a user quickly in a case of trouble.

Particular care should be ________ to the correct connection of accumulators for charging.

About one million people are ______ in this brunch of industry.

Computers have often been _______ of as extremely complicated calculators, but this is a very simple standpoint.

Unit 3. Electric Circuits. Their types and applications. Active vocabulary

Intervention - втручання Thermistor - термістор Voltage - напруга Current - струм (потік) Accidental - випадковий Capacitor – конденсатор to establish - встановлювати

to conduct - проводити to cease - припиняти to insert - помістити to wrap - загортати to bypass - пропускати Junction - з'єднання Dim - неясний

Parallel circuit – паралельне коло Source – джерело

Alessandro Volta (1745-1827) A lessandro Volta invented the first battery, the voltaic pile, in 1800. The very first circuits used a battery and electrodes immersed in a container of water. The flow of current through the water produced hydrogen and oxygen. The invention of the battery -- which could produce a continuous flow of current -- made possible the development of the first electric circuits.

Series circuit – послідовне коло Open circuit – Closed circuit – замкнуте коло розімкнуте коло

Short circuit – коротке замикання

Discussion

Think of the different types of electric circuits. What are the main differences they have?

What do they have in common?

Reading

Read the text below to match the terms on the left with their definitions on the right.

1	Closed circuit	a	A circuit in which the components are connected in line with one another and the wire. This type of circuit does not contain any three or more wire junctions
2	Open circuit	b	A circuit in which there are junctions of three or more wires. Components don’t "share» the same wire; instead each component has its own wire.
3	Short circuit	c	This circuit consists of three elements: a source of electricity (battery), a path or conductor on which electricity flows (wire) and an electrical resistor (lamp)
4	Series circuit	d	A faulty or accidental connection between two points of different potential in an electric circuit, bypassing the load and establishing a path of low resistance through which an excessive current can flow.
5	Parallel circuit	e	An electric circuit providing an uninterrupted, endless path for the flow of current.
6	Simple Circuit	f	An electric circuit in which the normal path of current has been interrupted, either by the disconnection of one part of its conducting pathway from another, or by the intervention of an electric component, such as a transistor.

Four parts of the Circuit S witch Energy Source Opens and closes Provides the “push makes current move around a circuit Wires Connect the energy source and load Load Converts electrical energy to another form

Types of Circuits

An electric circuit consists of the various conductors that lead from the negative to the positive terminal of a source of electricity. The four main parts of a circuit are: the source (battery), load (light bulb), control devices (switch), and connectors (wires). A closed circuit has a complete path for current to flow. An open circuit doesn't, which means that it's not functional. If this is your first exposure to circuits, you might think that when a circuit is open, it's like an open door or gate that current can flow through. And when it's closed, it's like a shut door that current can't flow through. Actually, it's just the opposite, so it might take awhile to get used to this concept. 

A short circuit is a low-resistance path, usually made unintentionally, that bypasses part of a circuit. This can happen when two bare wires in a circuit touch each other. The part of the circuit bypassed by the short circuit ceases to function, and a large amount of current could start to flow. This can generate a lot of heat in the wires and cause a fire. As a safety measure, fuses and circuit breakers automatically open the circuit when there is an excessive current. In a series circuit, electricity has only one path on which to travel. In the example to the right, two bulbs are powered by a battery in a series circuit design. Electricity flows from the battery to each bulb, one at a time, in the order they are wired to the circuit. In this case, because the electricity can only flow in one path, if one of the bulbs blew out, the other bulb would not be able to light up because the flow of electric current would have been interrupted. In the same way, if one bulb was unscrewed, the current flow to both bulbs would be interrupted.

Parallel circuits are like the smaller blood vessels that branch off from an artery and then connect to a vein to return blood to the heart. In a parallel circuit, electricity has more than one path on which to travel. In the example to the right, two bulbs are powered by a battery in a parallel circuit design. In this case, because the electricity can flow in more than one path, if one of the bulbs blew out, the other bulb would still be able to light up because the flow of electricity to the broken bulb would not stop the flow of electricity to the good bulb. In the same way, if one bulb were unscrewed, it would not prevent the other bulb from lighting up.

Language practice.