Science: Physics Flashcards
What is energy?
The ability to do work
The more energy something has, the more work it can do
Works transfers energy from one place to another or transforms energy from one type to another
Energy is always measured in Joules (J)
What are some types of Kinetic Energy and what are their definitions?
Movement/Kinetic: Energy possessed by a moving object
Light: Any form of energy on the electromagnetic spectrum(light). Often visible
Sound: Energy that travels as vibrating waves and can be heard by our ears
Heat: A measure of the total kinetic energy possessed by particles in a substance
Electrical: Energy that causes charged particles to move
What are some types of Potential energy and what are their definitions?
Gravitational: The stored energy in an object that is held over the surface of the Earth
Chemical: Energy stored within a substance, such as food and fuel, that may be released when the substance is burnt or digested
Nuclear: The energy stored within the nucleus of an atom
Elastic: Energy stored within a stretched or compressed object like a spring or elastic material
What does the Law of Conservation of Energy mean?
Energy cannot be created nor destroyed, only transferred or transformed
This Law basically just means that energy never disappears
The total amount of energy always stays the same. The total amount of input energy is equal to the total amount of output energy
In most energy transfers, energy can be transformed into several different types of energy, some of which may or may not be useful
What are Energy Flow Diagrams and how do you make them?
Energy flow diagrams are used to show energy transfers and transformations
Arrows are used to show the direction of energy movement and the forms of energy are labelled at each step
You don’t need to draw objects, you can simply write what they are and draw a box around them
What are the 5 points of Particle Theory?
Matter is made up of tiny particles
Particles of matter are all in constant motion
Particles of matter are held together by electric forces
There are empty spaces between particles, these spaces differ with each phase (solid, liquid, gas)
Temperature affects the speed of the particles. The higher the temperature, the faster the speed of the particles. (This last point is called the Kinetic Theory of Matter)
What is temperature and what does it indicate?
Temperature indicates how hot or cold something feels
It depends on how quickly the particles of a substance are moving
Temperature is a measure of the average kinetic energy of the particles
The particles in a hot substance are moving faster than the particles in a cold substance
Temperature is measured with a thermometer and the unity are ˚ C
What is the difference of Heat and Temperature?
Heat is the total amount of energy, temperature Is the average amount of energy
What is heat?
Heat is a form of energy
Heat describes the total energy of all particles within an object
Heat is measured in Joules
What is Conduction?
Conduction is the process of heat transfer by vibrating the particles
When something heats up the particles vibrate, adjacent particles are vibrated by these particles and so on and so on
The passing on of the vibration causes the heat to also be passed on
What is convection?
Convection is the transfer of heat in a liquid or gas due to less dense, warmer matter rising and denser, cooler matter falling
The particles in liquids and gases are more loosely arranged and therefore can flow
Gases and liquids are called fluids because they have the ability to flow
When particles in fluids are heated, they spread out making the matter less dense.
What is radiation?
Heat can be transferred without particles vibrating or flowing
Radiation is the movement of heat in the form of electromagnetic waves which can travel through a vacuum
These waves travel at the speed of light. Infra-red radiation is heat energy transferred this way
All objects release/emit some infra-red radiation
When heat radiation hits an object it can either be absorbed, reflected or transmitted
What is Static Electricity
Static electricity is a collection of negative charges that jump from one object to another
What are electrostatic forces?
Opposites attract – positively and negatively charged object will move to stick together
Same charges repel – negative and negative or positive and positive want to push each other away
These attraction or repulsion forces are called electrostatic forces
Examples of good and bad static electricity
Carpet static – bad when you get shocked
Aircraft refuelling – bad can cause an explosion
Photocopier – good this is how photocopiers work
Lightning – both. Bad if you get struck by lightning. Some artworks are creating by lightning hitting silica sand
What is static electricity?
Collection of negative charges that jump from one object to another
Easier for atoms in some materials to give away electrons, atoms in some materials are happy to accept them
Materials like rubber, fur plastic give away electrons, to materials like hair, skin, metal
Jumping of electrons from one object to another = Static Electricity
Object that gives away electrons = Positively charged
Object that accepts electrons = Negatively charged
Static charge leaks away into surroundings, returns materials to original state
If build-up continues, electrons jump from negatively-charged to positively-charged = Equalising the charges
- When done, they release energy
○ Light energy
○ Electrical energy
○ Sound energy
○Heat energy
What are Good & Bad Static Electricity
Good & Bad Static Electricity
- Carpet Static - Bad: when you get shocked - Aircraft Refuelling - Bad: can cause an explosion - Photocopiers - Good: because that's how they copy work - Lightning - Both, Bad: If you get struck by lightning. Good: Artworks created by lightning hitting silica sand
What is Current Electricity
Continuous movement of electrons through a conductor
Energy from moving electrons is transformed into different forms of electricity
- Eg. Light, Heat, Sound
Electricity used in homes is not static, made from flow of negative electrons, usually through metal wire or other electrical conductor, around a circuit
Movement of charge = Current Electricity
What is Current
Rate of flow of electrons from one point to another
Measured by ammeter, unit of measurement = amps
Current = Actual “substance” flowing through wires of the circuit (Electrons)
What is Direct Current
Batteries & cells produce direct current, electrons travel in one direction
Whats is Alternating Current
Electrons travel in both directions, back & forth along a wire
Used at power outlets in buildings because it generates more power, easier to transmit & voltage can be increased/decreased using transformers
What are the currents in parallel and series circuits
In series circuit, current is the same at any point
In parallel circuit, current distributed across the branches
Example of distribution of current through parallel circuit
- Series of water pipes arranged like parallel circuit, rate of water flow may differ between branches/sections of parallel circuit
What is Voltage
Measure of amount of energy, supplied to the charges by the voltage source (Supply voltage), used by the charges as they pass through a component of a circuit
Voltage is pressure that pushes the current through the circuit
Measured by voltmeter, unit of measurement = Volts
Voltage is high when electrons are supplied a lot of energy or losing a lot of energy. Voltage = Low if electrons lack energy
What is Resistance
Measures how difficult it is for an electric current to flow through a material/component
Resistance is friction that obstructs the flow of current through the circuit (Eg. Rocks in river)
If resistance = High, electrons lose energy, voltage & current decreases
Measured by digital multi-meter, unit of measurement = Ohms
What are 3 Factors That Affect Resistance
Material the wire is made from
Length of the wire - Longer the wire, the more resistance there will be
Thickness of the wire - Thinner the wire, the more resistance there will be
What is Ohms Law
Gives relationship between voltage, current, resistance in a circuit
Current passing through a conductor is proportional to the voltage over the resistance
What are the Formulae for Ohms Law
Voltage = Current x Resistance
Current = Voltage / Resistance
Resistance = Voltage / Current
What are electrical circuits?
Electric Circuits
An electric circuit is the path electrons take to transfer their energy
Electrons are conducted through the circuit, from the negative terminal of the energy source to the positive terminal
Electric circuits are made up of components which have universal symbols
There are two types of circuits:
Series
Parallel
What are some main components of Electrical Circuits?
Components of Simple Electrical Circuits
An energy source (Battery or cell)
An energy user, e.g. a lightbulb
Metal wires connecting everything
Often there is a switch turning the circuit on or off – A break in an electrical circuit will stop the flow of electrons and turn off the energy user
Chemical Energy as an energy source?
Chemical Energy as an Energy Source
A chemical cell stores chemical energy and transfers it to electrical energy when a circuit is connected
A battery is made up of 2 or more chemical cells
The chemical energy of the cells us used up as it pushes the current round a circuit
The current travels from the negative terminal of the battery, through the circuit, to the positive terminal of the battery
Was that… A BEKY MOMENT
How are series circuits arranged, what happens if a bulb blows out?
Series Circuits
The components are connected end-to-end, one after another. They make a simple loop for the current to flow around. If one bulb ‘blows’ it breaks the whole circuit and all the bulbs go out.
