2T electricity 4.4

• Natuurkunde
• Middelbare school
• vwo
• Leerjaar 2

Electricity

§4  Power and energy

Welcome!

Homework from last time

1, 3, 4, 6, 7, 8

Learning objectives

• You can explain the meaning of 'electrical power'.
• You can perform calculations with the electrical power of a device.

• You can analyse mixed circuits (series and parallel combined)

Mixed circuits

It's like a puzzle

3 important rules:

         1. The current gets divided in parallel and is the same in

             series.

         2. The voltage gets divided in series and is the same in

              parallel.

         3. Ammeters are always in series, voltmeters are always

              parallel!

Let's try!

Which one of these uses 

more energy?

Which one of these uses 

more energy?

It depends on the time!

Electrical power

The electrical power is the amount of Joules that an electrical device uses each second.

We measure the power in Watts [W]

Electrical power

The electrical power is the amount of Joules that an electrical device uses each second.

We measure the power in Watts [W]

What does the electrical power depend on?

Electrical power

P is the electrical power in W

U is the voltage in V

I is the current in A

P=U⋅I

Your phone charger works on a voltage of 12V.
The package says that it delivers 20W to the
phone. Calculate the current that runs
through the charger.

Working on the exercises

Read: p. 139 - 141

Make: 2, 4, 5, 6, 8

And: 11 from paragraph 3

Not finished? --> Homework!