II. Read and translate the text.

 

Among the most common meters used there are the ohmmeter, the ammeter and the voltme­ter. The ohmmeter is used to measure the value of resistance. It consists of a millimeter cali­brated to read in ohms, a battery and resistors. The meter is connected in parallel and the circuit is not opened when its resistance is measured. The readings on the scale show the measured value.

The ammeter is used to measure the value of current. When the ammeter is used the circuit should be opened at one point and the terminals of the meter should be connected to it. One should take into consideration that the positive terminal of the meter is connected to the posi­tive terminal of the source; the negative termi­nal - to the negative terminal of the source.

The ammeter should be connected in series. The readings on the scale show the measured value.

 

III. Find English equivalents.

 

Клемма, батарея, положительный, отрицательный, шкала, измерять, среди, вольтметр, резистор, омметр. 

 IV. Add necessary letters.

 

Meas-re, vol-metr, o-m-etr, bat-ery, resis-ance, com-on, am-etr, mil-im-tr, par-aller.

 

V. Finish the sentences.

1. The ohmmeter is used……..

2. The meter is connected……..

3. The ammeter is used to…………..

4. When the ammeter is used………

5. One should take into………..

 

VI. Make up the sentences.

1. Ohmmeter, the, most, used, common, there, meters, the, the, ammeter, are, and, the, voltme­ter, among

2. Measure the resistance used to value ohmmeter the of is.

3. Opened is the c in and circuit is when not parallel its is measured resistance meter the connected.

4. The current is of to value ammeter used the measure.

5. The be in connected ammeter series should

 

VII. Solve the following problems:

1.Suppose the ammeter scale reads 1.9 amp, the voltmeter scale reads 2.4 V; how much is the value of resistance in the measured circuit?

2.Suppose the ohmmeter scale reads 75 ohms, the voltmeter scale reads 220 V; how much is the value of current in the measured circuit?

3.Suppose that you have a series circuit consisting of three resistors and a voltage source. Ri = 0.18 ohm, R₂= 1.15 ohms, R₃ = 2 ohms, 1=10 amp. Find the voltage drop across each resistor; find the value of voltage in the circuit. Suppose Rx gets open. What does it result in?

4.Two resistors are connected in series. R] = 7,000, R₂ = 2,200, 1 = 110 amp. Find the voltage drop across each resistor. Suppose no current passes through the circuit, what does it result from?

 

VIII. Complete these sentences using while. Follow the model.

 

Model: The ammeter is used to measure the value of current....

The ammeter is used to measure the value of current while the ohmmeter is used to measure the value of resistance.

1.The ohmmeter is used to measure the value of resistance     

2.The ammeter is connected in series

3. When the ammeter is used to measure the value of current the circuit

should be opened

 

 

IX. Pair work. Put these questions to your group mate. Let him/her answer them.

 

1.What is the ammeter used for?

2.What is the voltmeter used for?

3.What is the ohmmeter used for?

4.What terminals does a meter have?

5.Should the measured circuit be opened when the voltmeter is used?

6.Should the measured circuit be opened when the ammeter is used?

7.In what way should the voltmeter be connected to the circuit?

8.In what way should the ammeter be connected to the circuit?

9.What is the difference between a voltmeter and an ammeter?

    10. What common meters are used to measure the values in a circuit?

 

 

ПРАКТИЧЕСКАЯ РАБОТА № 7

RESISTORS

 

 

Цели: Введение и активизация в речи лексики по теме «Резисторы».

Оборудование: комплект тестов, раздаточный материал.

 

 

                                       Vocabulary

I. Learn the words and expressions.

Capacity                                емкость

Power                                    мощность

Heat                                      теплота, нагрев

Rate                                      скорость, степень

To produce                           производить

To change                              менять(ся)

To vary                                  варьировать(ся)

Low                                        низкий

High                                      высокий

Fixed                                     постоянный

Any                                        любой

Variable                                переменный