SCX - Physics Energy Flashcards
Heat Energy
A form of energy that can be transferred. It is the total kinetic and potential energies of the particles that make up the object. Symbol = Q, Unit = J
Temperature
A measure of the average kinetic energy of the particles that make up a substance. Symbol = T, Unit = °C
Joule(s)
The unit for energy. Unit = J
Celcius
A temperature scale based around the melting and boiling points of water, Unit = °C
Kelvin
A temperature scale that starts from absolute zero, Unit = K
Absolute zero
The theoretical temperature at which all particles would stop moving (-273°C)
Solid
Particles are packed tightly in a fixed pattern. Gently vibrating but are held together by a strong force
Liquid
Particles are moving and can slide past each other. They are not held together in a fixed pattern. Held together by a weaker force
Gas
Particles are spread far apart and move about very quickly forces holding there movement cannot overcome there rapid movements
Thermal Conductor
A Thermal Conductor allows heat energy to flow through it
Thermal Insulator
A Thermal Conductor restricts the flow of heat energy through it
Thermal
Relating to heat energy
Easiest way to decide whether conduction is responsible for heat transfer
- Normally in Solids however there are rare instances where is also occurs in liquids and gases
- Objects are touching
- Objects are not moving to cause the transfer (Stationary)
When does Convection occur
Convection occurs when the particles are free to move. This means that the objects must either be a liquid or gas
How does Convection occur
Ek increases -> vibrates more -> Forces weaken -> Moves apart -> Volume increase -> Density Decreases -> Heat rises (vice versa)
Density Formula
D = m/V
Convection
The heat transfer process that occurs because objects are fluid. Their particles are free to move
Radiation
The heat transfers process that occus without the need for particles/can travel through a vacuum
Thermal Energy
The energy possessed by an object due to the movement of the particles within them.
Heat Transfer
The transfer of thermal energy between molecules within a system. An object can gain heat or lose heat, either heating up or cooling down
Equation for heat energy with Temp change
Q = mcΔT
Equation for Latent heat energy
Q = mL
m
mass kg
c
Specific Heat Capacity (J kg-1 °C-1)
ΔT
Temperature Change (°C)
L
Latent Heat (J Kg-1)
Specific heat capacity
The specific heat capacity of a substance is the amount of heat energy needed to change the temperature of 1kg of the substance by 1 °C
Latent Heat
A measure of how much heat energy is absorbed or released when 1kg of substance changes state without changing temperature
Conduction
The heat transfer process that occurs because objects are touching
Equation for Power
P = E/t
P
Power (Watts)
E
Energy (Joules)
t
Time (seconds)
Amplitude (A)
This is the maximum displacement of the wave from its equilibrium position, measured in metres (m)
Wavelength (λ)
This is the distance between two corresponding points in phase eg crest to crest, measured in metres (λ)
Time Period (T)
This is the time taken for one complete wave to pass a point, measured in seconds (s)
Frequency (f)
This is either the number of complete waves to pass a point each second, or alternatively the number of complete waves produced each second, measured in Hz or s-1
Wave Velocity (V)
The velocity of the wave is a measure of how fast a wave moves, measured in ms-1
Wave
Waves transfer energy without the transfer of matter
Oscillation of Longitudinal Waves
Parallel (Left and Right)
Oscillation of Transverse Waves
Perpendicular (Up and Down)
Examples of Transverse Waves (4)
- Water
- Light
- Electromagnetic (EMR)
- S Earthquakes
Examples of Longitudinal Waves (2)
- Sound Waves
- P Earthquakes
Micro (µ)
x10^-6
Nano (n)
x10^-9
Pico (P)
x10^-12
milli (m)
x10^-3
Equation for frequency
f = V/λ
Equation for time (waves)
T = 1/f
Similarities between Conduction and Convection
Both are methods of heat transfer. Both involve the movement of energy from a hotter region to a cooler region.
Differences between Conduction and Convection
In conduction, heat is transferred from one atom or molecule to another through direct conduct. On the other hand, Convection heat is transferred by the movement of the fluid itself.
(Note: Remember to define both and provide examples)
Describe heat transfer by radiation
Occurs when warm objects emit electromagnetic radiation. When they strike an object they are either absorbed, heating the object, or reflected. (+Define Radiation)
Describe solar radiation
A general term for the electromagnetic radiation emitted by the Sun. Includes all the wavelengths that make up the visible spectrum, and invisible wavelengths
Speed Equation
V = d/t
What is the speed of light / air
3 x 10^8 m/s
Electromagnetic Spectrum
Radio/TV - Microwaves - Infrared - ROYGBIV - Ultraviolet - X-Rays - Gamma Rays
Application/Uses of Radio waves
Communication (radio and TV)
Application/Uses of Microwave Waves
Heating food, communication (WiFi, mobile phones, satellites)
Application/Uses of Infrared
Remote Controls, Fibre optic Communication, Thermal imaging, night vision, motion sensors, heating or cooling things
Application/Uses of Visible light
Seeing and taking photographs/videos, fibre optic communication
Application/Uses of Ultraviolet
Security marking (fluoresce), Fluorescent bulbs, Getting a. sun tan
Application/Uses of X-rays
X-ray images (medicine, airport security etc)
Application/Uses of Gamma rays
Sterilising medicine instruments, treating cancer
Properties of mechanical waves
- Produces by disturbances in a medium
- Need medium
Properties of Electromagnetic waves
- Produced by disturbance in electric and magnetic fields
- No medium is necessary, can travel in a vacuum
The higher the frequency…
The higher the pitch
The higher the amplitude…
The louder the sound/ The brighter the light
Law of reflection
Angle of reflection is equal to angle of incidence
Index of refraction (n)
A ratio of the speed that light travels through a vacuum, compared to the speed that light travels through a specific medium
Index of refraction formula
n = c/v
c = Speed of light in a vacuum, m/s
v = Speed of light in the medium, m/s
Snell’s Law
n(1) sinθ(i) = n(2) sinθ(r)
Mega
x10^6
What is Particle Theory
All matter is made of particles which are always moving
°C to K
+273
Km/h -> m/s
/3.6
Law of Energy Conservation
Energy can neither be created nor be destroyed but can only be converted from one form to another
Magnetic metals (Ferro magnetic material)
- Iron
- Nickel
- Cobalt
Paramagnetic Material
Cannot Magnetise
Soft metal
Easy to magnetise but also loses its magnetism easily. Used in electromagnets and transformers
Hard Metal
Harder to magnetise and also does not lose its magnetism easily. Used in permanent magnets
Where do field lines run
North to South
Magnetic Domains
All pieces of iron and steel are made of millions of these tiny magnetic domains
Unmagnetised piece of iron
Magnetic domains are pointing in all directions so cancel out each other. Overall the iron is not magnetised
Magnetised piece of iron
Magnetic domains pointing the same way. The iron is magnetised
How is the direction of current symbolised
. = current towards (anti-clockwise)
x = current away (clockwise)
Magnetic field calculating
B = KI/d
K
Magnetic Constant = 2x10^-7
B
Strength of magnetic field around the wire is tesla, T
I
Current in amperes of amps (A)
Solenoids
- Controllable
- A coil of wire
Right hand Solenoid rule
Curl fingers in direction of conventional current, thumb will point to the North
How to make a field stronger
- By increasing the current through the wire (increasing Voltage or Decreasing Resistance)
- By placing a strong iron core in the middle of the coil
- By increasing the length of the wire (increasing num of loops or increasing the Area of the coil)
Uses of Electromagnets
- Used on cranes in steel-works and scrapyards
- Used to remove splinters of iron or steel
- Electric bells/doors
Constructive magnetism
2 magnetic fields which move in the same direction, they add or amplify the magnetic field
Destructive Magnetism
2 magnetic fields which move in opposite directions, they cancel out or subtract
Alternating current (AC)
An electric current that periodically reverses direction and changes its magnitude continuously with time
Feature of AC Generator
- Contains 2 slip rings
- Within a magnetic field
Uses of AC generator
Used in homes, industries and utilities for powering appliances and machinery
Features of DC Generator
- Contains split ring
Main Nuclear Fuels
Uranium and Plutonium
How is the energy from the sun transferred that falls on earth
By radiation, mostly visible light and infrared radiation
Harnessing solar energy
Solar energy has a low energy density, which means large collecting devices are required
Advantages of Solar energy
- Renewable source
- In many places on earth this is a reliable source
- Produce no greenhouse gases or pollution
- Can be generated in remote locations where they don’t have energy
Disadvantages of Solar energy
- Expensive
- Visual Pollution
- Some places on earth where this is not a reliable source
Conditions for critical angle
- More optically dense to less optically dense substance
- Angle of refraction in 90deg
Critical Angle
The incident angle which causes an angle of refraction to be 90deg.
Diffraction
The bending of a wave as it passes through a small opening or around a barrier
Photons
- Fundamental particles which make up all forms of EMR
- A photon is a massless “packet” or a quantum of EM energy
Diffraction proportions
Diffraction is proportional to the wavelength but inversely proportional to the distance
Wavelength of 4G/45/Bluetooth
High frequency radio waves
Why is Radioactive Waste bad
Radioactive waste is hazardous due to its potential to emit radiation, which can harm living organisms and the environment
Why is Radioactive Waste bad points
- Radioactive exposure
- Longevity
- Contamination
- Accidents and Leaks
How Radioactive Waste is managed
- Segregation
- Containment
- Transportation
- Disposal
- Monitoring
Advantages of Nuclear Power
- Low Energy Gas emissions
- High Energy Density
- Reliability
- Technological advances
- Reduced Dependence on Fossil Fuels
Disadvantages of Nuclear Power
- Radioactive Waste
- Risk of Accidents
- Limited Fuel Supply
- High Initial Costs
Magnetic Fields
An area where a ferromagnetic metal or charge experiences a force.
photoelectric effect
Occurs when photons of light strike a piece of metal and cause a potential difference to occur by displacing electrons.
kilo (k)
x10^3
mega, M
x10^6
giga, G
x10^9
Why can you not see around a wall but hear sounds around a wall?
Because sound has a large wavelength so there is more bending and a short wavelength for light so there is less bending
Wave nature of light
Diffraction or Interference
What is the point of nuclear fission for nuclear power
The energy from the fission reaction is used to heat the water to steam which turns the turbines
