Everything Science Grade 11

CHAPTER 19. ELECTRIC CIRCUITS 19.3

Therefore,

1

R

=

1

R 1

+

1

R 2

=

1

2

+

1

4

=

2 + 1

4

=

3

4

T herefore, R = 1,33 Ω

Step 4 : Apply Ohm’s Law

V = R· I

∴ I =

V

R

=

12

4

3

= 9 A

Step 5 : Write the final answer

A 9 A current is flowingin the circuit.

Example 6: Ohm’s Law II

QUESTION

Two ohmic resistors (R 1 and R 2 ) are connected in serieswith a cell. Find the resistance of

R 2 , given that the current flowing through R 1 and R 2 is 0,25 A and that the voltage across

the cell is 1,5 V. R 1 =1 Ω.

SOLUTION

Step 1 : Draw the circuit and fill in all known values.

V =1,5 V

R 1 =1 Ω

R 2 =?

I=0,25 A