Resistance in series and parallel - Mrs Physics



Resistance in series and parallel

Resistance is measured in OHMS (()

Resistance opposes the flow of electrons or charge.

Resistance in series

To find the total resistance in series we add up all the individual resistances

RT =R1+R2+R3

For example what is the total of a 5( , 7( and 15( resistor in series?

R1=5(

R2 =7(

R3=15(

RT =R1+R2+R3

RT =5+7+15=27(

Resistance in Parallel

Adding resistors in parallel reduces the total resistance of the circuit (It is worth noting that the total resistance will be lower than the biggest resistor, use this for estimations!)

The formula looks quite complicated and causes problems but with modern calculators it becomes an easy sum to work out.

[pic]

For example what is the total of a 5( , 7( and 15( resistor in parallel?

R1=5(

R2 =7(

R3=15(

[pic]

On the calculator

[pic]

Find the total resistance of the following resistors in parallel. For each one draw the circuit and summarise the question before starting.

a) 6 ( + 4 (

b) 12 ( + 8 (

c) 500 ( + 200 (

d) 10k( + 100k(

e) 5 x 15 (

f) 25 ( + 100 ( + 75 (

[pic]

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Y

Find the total resistance of this network

8 Ω

2 Ω

5 Ω

4 Ω

4 Ω

4 Ω

4 Ω

2 Ω

3 Ω

3 Ω

3 Ω

3 Ω

3 Ω

3 Ω

6 Ω

6 Ω

6 Ω

14 Ω

20 Ω

28 Ω

؀ࠢࡃࡄࡻ࢐ࣰࣣ࣭ࣤࣧࣨ࣪࣫औकङचडढषसहऺ़ऽिीृॄॆेॊोॎॏ॒॓ॕॖक़ग़ज़ड़१२३४६ঃ਽ਿસહ18 Ω

18 Ω

18 Ω

12 Ω

24 Ω

48 Ω

48 Ω

X

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