YR2_T2_LSN11

• Science
• Middelbare school
• havo, vwo
• Leerjaar 2

Get ready

• Your Macbook (join the LessonUp)
• Your notebook.
• Your textbook.
• Pen & highlighter

YR2_T2_LSN11

Recap Topic 2

Plan for today

• Recap T2 
• Study for science on your own

T2.1 Learning goals

I can:

• Give examples of different energy sources
• Identify different forms of energy
• Identify the type of energy conversion that takes place
• Explain the difference between renewable and non-renewable energy and identify which one applies
• Explain the difference between sustainable and non sustainable energy sources and identify which one applies

Energy

Most common forms of energy:

Law of conservation of energy

Energy is not created or destroyed

Energy can be transformed from one form 

to another

What is “lost” energy?

Energy is never destroyed, but some energy conversion is not useful for us

Example: Your macbook heating up, instead of converting the electrical energy to only light and sound → we “lose” energy in the form of heat

Energy sources

Renewable = renews itself

non-renewable =  runs out, wont be able to use it forever

T2.2 Learning goals

I can…

• Explain the three different types of heat transfer.
• Identify which type of heat transfer is present in a situation.
• Explain the difference between conductors and insulators and describe how they should be used.
• Identify if a chemical reaction is exothermic or endothermic.
• Explain the effect of catalysts on chemical reactions.

Heat transfer

Heat can easily be transferred from one place to another.

Heat always moves from warmer to cooler places.

Heat transfer happens in 3 ways:

Conduction

Heat transfer through direct contact between the particles in a substance

• Conductors: good at conducting heat - metals; copper, silver
• Insulators: not good at conducting heat - plastic, cork, air, wood

 Endothermic

When a chemical reaction needs heat, it's called endothermic.

Exothermic

Chemical reactions that release thermal energy(heat) to the environment are called exothermic.

Catalysis

Each reaction needs energy to get started → activation energy

• Example: Heat is needed to start a fire (ignition temperature)

The activation energy can be 

lowered by catalysts 

(certain molecules) 

There are also catalysts 

in your body, 

they are called enzymes

2.3 Learning goals

I can…

• Explain what electrical energy is made of.
• Explain what current is, along with its unit of measurement.
• Explain what voltage is, along with its unit of measurement.

Current

A current (I) is how many electrons flow past every second.

 

Measured in Amps (A) with an ammeter

Voltage

 Voltage (U) is how much electrical energy each electron is carrying. 

 

Measured in Volts (V) 

with a voltmeter

Power

Power (P) is the amount of electrical energy used per second by a device.

Measured in Watts (W)

Watts is also J/s (joules per second)

Calculate 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)

Energy cosumption

All electrical devices use energy  → energy consumption

The amount of energy can be calculated with the formula:  E = P · t

E = Energy (in Joules)

P = Power (in W)

t = time (in s)

Energy cosumption

An electric kettle using a current of 2.17 A takes 1 minute and 54 seconds to boil the water.

Calculate the energy consumption of the kettle in kJ.

Answer:

E = P · t

• P = U · I = 230 · 2.17 = 499.1 W
• t = 60 + 54 = 114 s

E = 499.1 · 114

P = 56 897 J = 56.9 kJ

2.4 Learning goals

I can…

• explain the basic components necessary for building a simple circuit.
• draw circuit diagrams by using the circuit symbols.
• explain the advantages and disadvantages of a series circuit.
• calculate the current or voltage at various points in a series circuit.
• explain the advantages and disadvantages of a parallel circuit
• calculate the current or voltage at various points in a parallel circuit
• use an ammeter or voltmeter to properly measure the current or voltage at a certain point in a circuit.

Basic circuit

Copper wire connects the voltage source to the device and back again. When the switch is closed the electricity can flow through the wire and light the bulb.

Drawing a circuit

These symbols make drawing circuits easier

Measuring current

Ammeter:  is used to measure the current 

The current is measured in amps (A) 

The ammeter has to be connected in series with the device.

Measuring voltage

Voltmeter: is used to measure the voltage

The voltage is measured in volts (V)

The voltmeter has to be connected in parallel to the device.

Circuits - Series

• All components are in the same loop, end to end.
• There is only one direction in which the current can flow.
• The same current throughout the entire circuit.
• The voltage is shared by all components within the circuit.

Circuits - Series

Every ammeter will show the same value.

The voltage is shared by all components.

Circuits - Parallel

• Multiple loops or paths for the current to flow through.
• The current is divided over every pathway.
• The voltage is the same for all components.

Circuits - Parallel

The voltage is the same for all components, 

the current is divided.

The current only divides equally if components are the same.

2.5 Learning goals

I can…

• explain why a vegetarian diet is more sustainable
• explain how pesticides can accumulate in the food chain and kill predators
• explain how different kinds of pollution can lead to long term problems
• explain what the greenhouse effect is and how extra gasses can enhance this and cause global warming
• use the three R's to identify ways to live more sustainable

Food energy

All of the energy of our food comes from the sun

A lot of that energy is 'lost' 

By eating less (or no) animals 

we 'waste' less energy

Dietary Choices

You could choose to completely adapt your diet/lifestyle:

1. Vegetarian - You do not eat any meat at all, you could eat dairy & eggs

2. Vegan - You do not eat any animal products at all, and sometimes also avoid using things made from animal (leather / wool).

3. Pescatarian - You are basically a vegetarian that does eat fish.

Make sure you discuss this with your parents/guardians before changig your diet, especially when you are still growing!!

Pesticides

Other things that do NOT help the environment:

1. Pesticides (to kill insects on crops)

2. A lot of transport (fuel usage)

3. Use of antibiotics for animals

All this builds up in the food chain before it gets to us

This is called accumulation

Organic food is produced without 

the use of pesticides

Greenhouse effect

The earth is absorbing the heat of 

the sun like a greenhouse.

This is causing the earth to warm up 

which is known as the Greenhouse effect.

A continued greenhouse effect is 

now leading to Global Warming.

Greenhouse effect

Greenhouse gasses such as CO2 and Methane 

cause a bigger greenhouse effects.

Heat (radiation) can't leave the atmosphere. 

Earth heats up faster(global warming). 

This is called an Enhanced greenhouse effect

Sustainable living

How can we live more sustainably?

The three R's:

• Reduce
• Reuse
• Recycle

Questions?