Physics End of year

What are the four magnetic materials?

Iron, Steel, Nickel, Cobalt

How would you find out which materials are magnetic?

See if they are attracted to a magnet

What is a magnetic field?

the area around a magnet in which the effect of magnetism is felt

What direction do the magnetic field lines go?

North to south

What does the proximity of the magnetic field lines tell you?

How strong the magnet is

How does a compass work?

A permanently magnetised needle is placed so that it can rotate freely. The Earth's magnetic field exerts a force on the compass needle, causing it to rotate until it comes to rest in the same direction as the magnetic field.

Where is the Earth’s magnetic field the strongest?

The poles

How do you magnetise something?

Stroke it with a magnet

How do you demagnetise a magnet

Drop it or heat it

Why does iron make a better electromagnet than steel

Iron holds its magnetism for shorter time so the magnet isn’t permanent.

How can an electromagnet be turned on and off?

Break the circuit

How can you increase the strength of an electromagnet?

Increase the number of coils or increase the current

State uses of electromagnets

Electric buzzers, loudspeakers and scrapyard magnets

Why are electomagnets used in scrapyards

to sort through magnetic and mon magnetic material

What is produced around an electric current

A magnetic field

How does a magnet work?

Aligned domains create a magnetic force

Why does steel make a better magnet than iron?

It is harder to demagnetise and holds charge better

What are some types of energy? (3)

Heat, Kinetic and nuclear

What is the difference between heat and temperature?

Heat is transferred between objects, whereas temperature is a property of an individual object.

What went wrong for Captain Scott in the Antarctic?

He was malnourished and didn't get enough energy.

Why is energy important?

It powers many things like computers, cars and us.

What is thermal conduction?

the transfer of energy as heat through a material

How is heat transferred by conduction?

particles are heated and gain energy which causes them to vibrate and collide with other particles, transferring the heat energy

Why do some things feel hot or cold?

If it's a thermal conductor, it quickly conducts energy away, leaving our hand feeling cool.

How is heat transferred quicker in a metal?

Metals have free electrons that are not bounded to the atoms.

What is a convection current?

the flow that transfers heat within a fluid

What happens in a convection current?

less dense particles rise, cooler, denser materials sink, creating a cycle of motion that transfers energy throughout the fluid.

what is an example of a convection current?

A lava lamp

What colour is good at absorbing and emitting?

black or dark colours

What colour is bad at absorbing and emitting?

white or light colours

Why should a kettle be silver and not black?

silver reflects light from inside back in. That means that it won't radiate infrared light much when it gets hot. That then means that less energy is needed to get it hot.

Why are zebras striped?

black stripes would absorb heat in the morning and warm up zebras,whereas white stripes reflect light more and could thus help cool zebras as they graze for hours in the blazing sun. this is Thermoregulation

how is global warming caused?

As greenhouse gas emissions blanket the Earth, they trap the sun's heat

What effect have humans had on the CO2 level?

Human activities have raised the atmosphere's carbon dioxide content by 50% in less than 200 years.

What evidence is there that humans have caused climate change?

Carbon dioxide from human activity is increasing more than 250 times faster than it did from natural sources after the last ice age.

What happens to two objects temperatures as heat flows between them?

The heat transfer continues until the two objects are at the same temperature.

How does insulation work around the home?

trapping pockets of air

Why would something have more heat energy?

Because it is warmer or has more mass

What is the best conductor?

Metal

What is an insulator?

Something that does not allow heat to pass through

What is a conductor?

Something that allows heat to pass through

Why don’t insulators transfer heat quickly?

They don’t let heat energy move through them easily

What happens to a fluid when heated?

Its molecules gain heat energy which causes them to move faster