3T Electricity 1.1

• Natuurkunde
• Middelbare school
• vwo
• Leerjaar 3

Electricity

§3  Electricity in the home

Welcome!

Who am I?

• Former student @ haarlemmermeerlyceum
• Physics at TU Delft
• Basketball, cycling, chess
• Teaching

Plan of today

1. Testing your knowledge of Chapter 1

2. Discussing §3 (taking notes)

3. Example exercise

4. Working on exercises yourself

5. Discussing exercises

True or false:
A power station turns natural gas, coal or other fuel into electrical energy.

1. True
2. False

What is the right relation between power and energy?

1. E = P/t
2. E = P*t
3. E = t/P
4. E = U*I

True or false:
An induced voltage can be obtained with a magnet and a coil.

1. True
2. False

A 10W LED light is used for 5
minutes. How much energy has
the LED used in this period?

1. 50 J
2. 5 kJ
3. 3 kJ
4. 300 J

True or false:
If we want the secondary voltage to be lower than the primary voltage, we should make sure that the secondary coil has more turns than the primary coil.

1. True
2. False

The power drawn by the primary
coil is ... the power drawn by
the secondary coil.

1. Higher than
2. Lower than
3. Equal to

Let's start with §3!

dfa

Electrical power

• The current through a lightbulb is the amount of electrons that passes through the lightbulb per second. 
• The voltage across a lightbulb is the amount of energy that each electron carries.
• The power is the amount of energy that the lightbulb uses per second.
• How does this work for a group of appliances?

A group of appliances consists of a
washing machine (2.1 A), a vacuum cleaner
(0.9 A) and a TV (0.5 A).
Calculate the power that is drawn by this group.

Measuring energy

How many Joules is 1 kWh?

1 kWh costs €0.23

Working on the exercises

During the lesson: 4, 5, 7

More challenging exercises: 6, 8, 9

Homework: 1,2,3