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2. Read these common and decimal fractions:

1/3

2/5

5/8

7 1/2

9 5/8

15 8/9

0.23

0.009

10.01

205.35

79.31

0.0003

Unit Four [4]

1. A) Cover the right column and read the English words. Translate them into Russian and check your translation.

b) Cover the left column and translate the Russian words back into English.

current

[ˈkʌrənt]

электрический ток

resistance

[rɪˈzɪstəns]

сопротивление

voltage

[ˈvoultɪdʒ]

вольтаж, напряжение

to suppose

[səˈpouz]

предполагать

law

[lɔː]

закон

Ohm’s Law

R = 

V

Resistance equals voltage divided by current.

I

I = 

V

Current equals voltage divided by resistance

R

V = IR

Voltage equals current times resistance.

Problem

Suppose that resistance equals one volt and current equals one ampere.

How much is the resistance?

Solution

R = 

V

I

1V

= 1 ohm

1 amp

V = 1V

I = 1 amp

R = ?

2. Solve the following problems and read them.

Model: – How much is 10 times 4?

– 10 times 4 equals 40.

1) 7 × 7 =

5) 350 × 2 =

9) 49 : 7 =

13) 20.2530

2) 2.5 × 3 =

6) 3.5 × 10 =

10) 75 : 25 =

14) 7.5 : 5 =

3) 10,050 × 2 =

7) 2,000 × 5 =

11) 3,500 : 35 =

15) 40.8 : 4 =

4) 100 × 0.5 =

8) 0.12 × 2 =

12) 10.25 : 10 =

16) 15.5 : 3=

3. Solve the following problems using the formulas of Ohm’s Law.

Model: – Current equals 5 amp; resistance equals 10 ohms. How much is the voltage?

– Voltage equals current times resistance. 5 × 10 = 50 V

1) R = 80 ohms

V = 55 V

I = ?

2) R = 10.25 ohms

I = 35 amp

V = ?

3) V = 50.05 V

I = 120 amp

R = ?

4) I = 10,500 amp

V = 2,000 V

R = ?

5) V = 20.05 V

R = 0.015 ohm

I = ?

6) I = 0.24 amp

R = 1.36 ohms

V = ?

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