Physics Flashcards
What is an insulator?
It is a substance which does not allow electricity to pass through.
What subatomic particle is responsible for electrostatic charge?
Electrons are responsible.
What is an electrical conductor?
A material which allows electricity to pass through.
What is the difference between AC and DC current?
DC - current that is always in the same direction.
AC - current that repeatedly changes direction.
What is electrical charge measured in?
Charge or Q is measured in coulombs, C.
What are properties of magnetics?
They have two poles.
Like poles repel
Opposite poles attract
Forces are strongest the closer the magnetics are.
What’s the formula for current?
Charge Q / Time T
What’s the formula for resistance?
Voltage / Current
Define resistance.
It is the measure of the opposite to current flow in an electrical circuit.
Describe a soft magnetic material
Easy to magnetise but easy to demagnetise.
Describe a hard magnetic material
Hard to magnetise but hard to demagnetise.
Name key points about magnetic fields.
Predicted using the right hand rule.
Fields can be controlled by controlling current.
Clockwise - South
Anti-clockwise - North
Name some typical UK voltages.
Transformer - 11kw - 33kw
Transmisison - 275kv - 400kv
Consumer use - 230kv
What is Faraday
Faraday represents 1 mole of electrons.
equal to 96,500 coulombs
How do you calculate charged transferred?
Charge Q = Current I x time t
Define charged transferred?
It is the amount of charge transferred during electrolysis.
What values are needed to calculate the mass of a substance?
Charge transferred
Faraday
Ar or Mr
What is the molar volume of gas?
It is 24dm3 or 24,000cm3
Name the properties of all electromagnetic waves.
Travel in a vacuum
Emit energy via radiation
Travel at the same speed in vacuum
What are the properties of long wavelengths?
low frequency
Low energy
What are the properties of short wavelengths?
High frequency
High energy
What does this mean?
Roman
Men
Invent
Very
Unusual
X-Ray
Guns
Radio waves
Micro waves
Infrared
Visible Light
Ultraviolet
X-Ray
Gamma
What’s the difference between red light and violet light?
Red light is the lowest frequency of visible light
Violet is the highest frequency of visible light.
What’s the difference between mass and weight?
Mass is a measure of the resistance of an object to acceleration.
Weight is a force of gravity acting on an object.
What’s Newton’s second law?
Force = Mass * acceleration
What’s the formula for acceleration?
Change in velocity / time
What’s the formula for velocity?
Change in displacement / time
What’s the formula for speed?
Distance / time
Define the term half-life.
Means the average time taken for half the nuclei in a sample of an isotope to decay.
Name the hazards if ionising radiation.
Can damage human tissue.
Damage DNA
Damage plant cells
Radiation poisoning.
How to calculate the speed of wavelengths?
First need velocity = wavelength * frequency.
Then divide the distance of the medium with the velocity to get speed.
Define an isotope
Each element can exist as more than one possible nucleotide.
Nucleotide of the same element are known as isotopes.
What’s a nucleotide
Any type of nucleus.
Characterised by the number of protons and neutrons it has.
Define the process of loosing/gaining electrons.
Ionisation
What kinds of radiation is emitted when nuclei decay?
Alpha
Beta
Gamma
Describe the random nature of emissions.
Not possible to predict nuclei decay.
No known cause.
No way to make it happen sooner.
What are the relative charges of the three types of radiation?
Alpha - +2
Beta - -1
Gamma - 0
Define penetrating ability of nuclear radiation.
How easily a type of radiation penetrates through materials.
What is the penetrating ability of Beta radiation?
Blocked by thin material
Not blocked by human skin
Penetrates several meters in the air.
What’s the penetrating ability of gamma?
Requires centimetres of dense material like lead to block.
Penetrate hundreds of metres in the air.
What’s the penetrating ability of alpha?
Blocked by sheet of paper.
Blocked by human skin
Penetrate few centimetres in air.
