page 18/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

Resistors

1

page 28/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

What is the purpose of resistor ?

To control or reduce the flow of current from a certain energy source .

2

page 38/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

Resistor

Types of resistors THE SYMBOLS .

THE UNIT .

Ohm

3

page 48/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

Fixed Resistor .

symbol

This resistor has a fixed value so you can not change the value.

  Variable Resistor .

You can change the value in terms ranging between zero and the maximum value of its.

symbol

4

page 58/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

Light Dependent Resistors LDR .

symbol

This resistor is changing by amount of light falling on it .

Thermal Resistor .

This resistor is sensitive to heat and change its resistance with temperature change . symbol

5

page 68/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

How we can measure the value of resistor ?

1) By using the multimeter ( directly )

pay attentionResistor does not have polarity

2) Resistor Color Code

6

page 78/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

How do we know which color corresponds to which number?

Answer: Using the Resistor Color Code Table

7

page 88/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

Handout 1 : A) Determine the nominal resistance value and the tolerance for the resistor shown below.

Solution:

Nominal value = 10102= 1,000

Tolerance = 5%.

___ ___ 10 ____ % 1

Brown =1

0

Black =0

2

Red =2

5

Gold = 5%

8

page 98/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

B) Determine the nominal resistance value and the tolerance for the resistor shown below.

Solution:

___ ___ 10 ____ %

Resistor nominal value = 39105 = 3,900,000 = 3.9M.

Orange =3

3

White =9

9

Green =5

5

Silver = 10%

10

Tolerance = 10% 9

Resistors in Series and Parallel Circuits

10

page 118/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

Resistors in Series and Parallel Circuits

Resistors connected in series to any resistor followed by the next resistor until both ends to connects voltage source , that’s mean the current passes in one direction .

Connected any resistors in parallel that the resistor parallel the next resistor until both ends to connects to voltage source, that mean the current passes in two or more as the number of lanes in the circuit.

parallel Circuits .

Series Circuits.

Which one from these circuits are series and parallel ?

11

page 128/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

Resistors in circuits

Ohm's law

Resistors in Series

When connected in series, the total resistance (Rt) is equal to:

Rt = R1 + R2 + R3 +…

The total resistance is always larger than any individual resistance.

Resistors in Parallel

When connected in parallel, the total resistance (Rt) is equal to:

1/Rt = 1/R1 + 1/R2 + 1/R3 +…

Due to this reciprocal relationship, the total resistance is always smaller than any individual resistance.

12

page 138/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

Quiz :

10 V

15 Ω

10 Ω

6 Ω a) Calculate the total current through the circuit.

Rt = 15 Ω +10 Ω + 6 Ω

Rt = 31 Ω

I = V/Rt = 10 V/ 31 Ω =0.32 A

1/Rt = 1/12 Ω +1/4 Ω + 1/6 Ω

1/Rt = 1/500m Ω

Rt = 2 Ω

12 Ω

4 Ω

6 Ω

b) Calculate the total resistor through the circuit.

13

Handout-2

page 148/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

14

page 158/21/2010

Vocational Pedagogy

M2 - Didactics and Teaching practice

VP-4 / AVP-1 - Lesson planning and Teaching techniques / Teaching practice

15