Science - Electricity Flashcards
What is electrical energy?
a type of kinetic energy
What is electricity
the movement from negative to positive due to electrons having a negative charge
Why is electricity a convenient energy
it can be easily be changed into other forms of energy such as light and sound
What is current electricity
the flow of electrons through a material
some materials allow the flow of electrons more easily than others which are called conductors
What are conductors
Materials where some of the electrons are free to leave and they can flow through the conductor in an electric current
What are insulators
In materials where electrons are tightly held and can’t leave. Electrical current will not flow but static electricity can build up
What is static electricity
where charges occur in surfaces (insulators) and don’t flow away immediately
What happens when objects are rubbed together (static electricity)
some electrons transfer from one material to the other
gaining electrons = negatively charged
losing electrons = positively charged
What are the dangers of static electricity
If enough charge builds up, a spark may jump from one to another
Water droplets can become charged in thunderstorms that create lightning
What are some uses of static electricity
Photocopiers and inkjet printers
Powder-coating metals
What are good conductors
copper, zinc, carbon
What do circuits need to move
a push (this is called voltage)
if there is no voltage, no electrons will move
What is a parallel circuit
where the components are compared side by side, which allow several different pathways for the current to flow around. If one bulb blows the other bulb will still remain as the circuit is still complete.
What is a series circuit
where the components are connected end to end in a loop. If one bulb or component brakes the whole circuit will go out and the circuit is not complete
What are some standard circuit symbols
Lightbulbs
Potentiometer
Battery cell
Wine
Speaker
Multiple batteries
What is current measured in
Amps (A)
What is a electrical current
the flow of rate of electrons
What is the law of conservation of energy
electric charge can neither be created nor destroyed in a closed system, the amount of charge remains the same
What is voltage
the voltage of a battery that tells us how much energy it provides to the components in the circuit. It provides energy to the circuit by supplying energy to all the electrons that flow through the circuit
What is resistance
the measure of how easy it is for the current to flow around a circuit.
the higher the resistance, the lower the current the flow around a circuit. the higher the current flow around the circuit, the lower the resistance
What is resistance measured in
Ohms
What are resistors
the component that resists current
if you add a resistor in series with a circuit, the current in the circuit will be lower than without the resistor.
What is power
how much energy (in joules) is transferred in one second.
power is measured in Watts (W)
How to calculate watts
watts= volts x amps
eg if the current is 2 amps and the voltage is 240V, then the power is 240 x 2 = 480 watts
What is the cost of electricity
the total amount of energy transferred by an appliance depending on
the power (higher power appliances transfer more energy than lower power ones)
the time that it is used form
What are kilowatt-hours
the energy transferred by an appliance measuring in kilowatt-hours
What is the equation for kilowatt-hours
power rating in kW x time in hours = the total amount of energy used
kW x hours = kWh
How do electricity companies charge you
the amount of kWh used
total kWh used x the price of one kWh = total cost
eg 2.4kW for 5 hours at 25 cents per kWh comes out at (2.4x5) kWh x 0.25 = $3
What are the 3 magnetic materials
Iron, cobalt, nickel. Steel can be magnetic as it contains a lot of iron
What is magnetism
an invisible force.
all magnets have a North and south Pole. like poles repl whilst opposite poles attract
How do magnets work
Magnets exert a force magnetic field around them. A magnet can exert a force on another magnetic material
What are magnetic fields
The strength shown by the density of lines
What is Earth’s magnetic field
the spin of earth cresting a magnetic field around the earth with North and South poles
What is the unit of magnet field strength
Tesla (T)
What is an electromagnet
where electrical charges flow in a wire, a magnetic field is formed around the wire
What is a solenoid
the length of wire that is looped or coiled around to make an electromagnet
Why are electromagnets useful
they can be charged and be switched on and off the strength
3 good insulators
Rubber, plastic, glass
