# Lesson 7 — 5.3 Series and parallel

This lesson
• Recap questions
• Resistance, voltage & current — Parallel and series
• Working on exercises.
1 / 11
Slide 1: Tekstslide
PhysicsMiddelbare schoolvwoLeerjaar 3

In deze les zitten 11 slides, met interactieve quiz en tekstslides.

Lesduur is: 45 min

## Onderdelen in deze les

This lesson
• Recap questions
• Resistance, voltage & current — Parallel and series
• Working on exercises.

#### Slide 1 -Tekstslide

A electrician is working on a series circuit with a current of 0,83 A flowing through it and a total resistance of 8 Ω. He adds two resistors of 4 Ω each to this circuit. After this he doubles the voltage over the circuit.

What will happen to the current flowing through the circuit after this?
A
You can't tell because you aren't given the voltage over the circuit.
B
It wil double.
C
It will be half as much
D
It will be the same.

#### Slide 2 -Quizvraag

A physicist wants to make a charge of 6,4∙10^-15 C flow through a wire. He knows the resistance of the wire is 25 Ω. He applies a voltage of 8 V over the wire. How long does a current have to flow through the wire to let the required amount of charge flow through it?

#### Slide 3 -Tekstslide

A physicist wants to make a charge of 6,4∙10^-15 C flow through a wire. He knows the resistance of the wire is 25 Ω. He applies a voltage of 8 V over the wire. How long does a current have to flow through the wire to let the required amount of charge flow through it?
Given:
- Required amount of charge: 6,4 • 10^15
- R = 25 Ω
- U = 8 V

How long does current have to flow through the write to reach the required amount of charge?

Working:
R = U/I                   I = U/R

Q = I • t                  t = Q/ I

I = 8/ 25 = 0.32 A
t = (6,4 • 10^15)/ 0,32 = 2 • 10^16 seconds

#### Slide 4 -Tekstslide

Different types of resistors
• What is an ohmic resistor?
•  What material can be used to make an ohmic resistor?
• Why do other materials not follow Ohms law?
• What does NTC stand for?
• What is the relationship between temperature and resistance in an NTC?
• What would the opposite of an NTC be called?
• What doe LDR stand for?
• What is the relationship between light and resistance in an LDR?

#### Slide 5 -Tekstslide

Different types of resistors
What is an ohmic resistor?
• A resistor where the resistance is the same regardless of the voltage.

What material can be used to make an ohmic resistor?
• Constantan

Why do other materials not follow Ohms law?
• An increase in voltage causes an increase in current in a circuit. This increases the temperature of the wire. This causes the resistance to increase.

#### Slide 6 -Tekstslide

Different types of resistors
What does NTC stand for?
• Negative temperature coefficient.

What is the relationship between temperature and resistance in an NTC?
• An increase in temperature causes a decrease in resistance and vice versa.

What would the opposite of an NTC be called?
• A PTC — Positive Temperature Coefficient.

What doe LDR stand for?
• Light dependent resistor.

What is the relationship between light and resistance in an LDR?
• If more light falls on the reistor its resistance will decrease and vice versa.

#### Slide 7 -Tekstslide

Resistance, voltage & current

Series and parallel

Equivalent resistance

#### Slide 8 -Tekstslide

Resistance, voltage & current — Series circuit
Resistors in series

Voltage in series

Current in series

Rtot=R1+R2+R3+...
Utot=U1+U2+U3...
Itot=I1=I2=I3=...

#### Slide 9 -Tekstslide

Resistance, voltage & current — Parallel circuit
Resistors in series

Voltage in series

Current in series

R1tot=R11+R12+R13+...
Itot=I1+I2+I3=...
Utot=U1=U2=U3=...

#### Slide 10 -Tekstslide

Homework
Exercise:
< 1, 2, 3, 4, 5, 7
> 3, 4, 7, 8, 9, 10