Science year 2.3: Electricity

• Science
• Middelbare school
• havo
• Leerjaar 2

Welcome back

Hopefully you had a good vacation

Continue with topic 2: Energy in the world

Inhalers make today an appointment with me

Next week different timetable

1: on Monday 9.00-9.45

2: on Wednesday 11.00 - 12.30 

Today

Reviewing 2.1 and 2.2

2.3 about electricity

Lesson up

Making exercises from the book and the brown bean project 

Which types of energy do you know?

conduction is heat transfer through...

1. solid materials
2. fluids and gasses
3. nothing
4. glass

What is a conductor

1. material that prevents heat from traveling
2. material that is very hot
3. material that lets heat travel easily
4. somebody that works in a tram

What is a catalyst?

1. something that makes substances burn
2. something that prevents materials to burn
3. something that increases the ignition energy
4. something that lowers the ignition energy

Learning goals

What is electrical energy made of

What is current, and what unit do we use for it

What is voltage, and what unit do we use for it

Calculate the power a devies uses with the formula P=U.I

Calculate the Energy a devies uses with the formula E=P.t

how energy consumption depends on power and time of use 

Name different sources of electricity

02:33

What is an insulator?

1. a material that does not conduct electricity
2. a material that conducts electricity
3. a clamp to connect two electric wires
4. a electric source

What is electricity?

Electricity is caused by the flow of electrons moving through a conducting material

- Those electrons go from the power source to the device

- In the appliance they leave their energy behind

- They go back to the power source to be charged.

The plastic around the wire is an insulator (cable jacket and wire insulation)

The coper wire is a conductor (stripped wire)

phet.colorado.edu

Assignment 

Make the following circuits work in the applet

- let a lightbulb burn with a battery

- let a lightbulb burn with a battery and a switch

- let 2 lightbulbs burn with a battery and a switch

There is a electrical current when...

1. the circuit is closed
2. when there is a electric source
3. when the wires are conductors
4. all three need to be true

Current 

How many electrons flow past every second.

 

Measured in Amps (A) 

with an am-meter

Voltage 

How much electrical energy each electron is carrying. 

 

Measured in Volts (V) 

with a voltmeter

How much voltage is in an electric socket at your home?

Voltage 

The mains socket has a voltage of 230V 

This can be dangerous and even deadly

24V is the safe limit  

Transformers raise/lower voltage

Power

The power of a devies is the amount of energy is uses every second.

The power is measured in Watts (W)

Watts is also J/s (joules per second)

Power

Power can be calculated with the formula:

P = U x I 

P for Power (in W)

U for Voltage (in V)

I for current (in A)

A devies has a battery of 12 V. There is a current going through the devies of 5 A. What is the power of this devies?

The formula is P = U x I
Witch of these is also correct?

1. U = I / P
2. U = P x I
3. U = P / I
4. U = P + I

A telephone has a 15 V battery. Its power in low energy mode is 45 W.
What is the current in the telephone?

Energy

Energy consumption is the amount of energy a devies uses during a certain time period.

1. Depends on the power of the devies  

2. Depends on the time the devies is on.

E = P x t

A water boiler takes 3 minutes to heat the water. It has a power of 2000 W.
How much energy did the boiler use.

1. 6000 J
2. 667 J
3. 0,015 J
4. 360000 J

Energy

Power

Time

Voltage

current

I

P

U

E

t

J

W

s

V

A

I

P

U

E

t

Now you should know

What electrical energy is made of

What current is, and what unit do we use for it

What voltage is, and what unit do we use for it

How to calculate the power a devies using the formula P=U.I

How to calculate the Energy a devies using the formula E=P.t

How energy consumption depends on power and time of use 

For next time

Make exercises of 2.3

If you have trouble making a question, write it down and ask about it in the next lesson.

Hand it in on classroom

(no homework done means no entrance)