Science - Physics - Electricity and Energy Unit 2
Solar cell transfers heat/light energy into ...
-> electrical
Torch transfers chemical energy from the battery into... into...
-> electrical to get to the lamp -> light and heat
Kettle transfers electrical energy into ...
-> heat
Candle transfers chemical energy from wax into ....
-> heat and light
Blown up balloon transfers elastic/strain energy into... as it flies around the room
-> kinetic
Sun transfers nuclear energy into ...
-> light and heat
Radio transfers electrical energy into ...
-> sound
1 cell to 1 bulb is 0.16 A. What is 10 cells to 10 bulbs?
0.16A
1000 watts = 1 kw = ...
1 KJ because 1 watt = 1 joule / second so 1 kw = 1000 watts
1000j is the same as ...
1 Kilojoule (1kj)
1 watt =
1 joule per second
1000 watt is the same as ...
1 kilowatt (1kw)
If one cell has a potential difference of 1.5, what would 3 of the same cells have?
1.5 x 3 = 4.5 v
How much energy in kWh would a 2 kW iron use if it was left on for a day
2 kW x 24 hours = 48 kWh
How much work do you do if you slide a book that weighs 12N along a desk for 20cm
20cm = 0.2m 12 x 0.2 = 2.4 j
If one cell and 1 bulb is connected and the cell has a potential difference of 2 v, what does the bulb have a potential difference of?
2v
A television uses 1000kj of energy in 3 1/3 minutes. What is its power rating?
3 1/3 minutes = 200 seconds 1000kj = 1 000 000 j 1 000 000 / 200 = 5000 watts or 5KW
If an electric drill uses 500j of electrical energy, the drill transfers 100j of this into sound and 100j into wasted heat energy. How much kinetic energy does this drill produce?
500j -100j - 100j = 300j
What is the difference between a cell and a battery?
A Battery is two or more cells connected but a cell is just one 'cell' which provides energy to push the current round the circuit
Explain Electrical energy
A battery transfers stored chemical energy as electrical energy in moving charges in wires. For example, electrical energy is transferred to the surroundings by the lamp as light energy and thermal energy
Explain kinetic energy
Moving things have kinetic energy. The heavier a thing is and faster it moves, the more kinetic energy it has. All moving things have kinetic energy, even very large things like planets and very small ones, like atoms
In a series circuit, does it matter where you put the open switch?
No because there is only one route for the electrons to go
What is non renewable energy?
Non-renewable energy resources cannot be replaced once they are all used up.
cost of electricity = (equation)
Number of kWh x cost per kWh
Explain light energy
Objects can give off energy in the form of light, for example : candles, the sun, a star, a light bulb. we can detect light energy using our eyes through our sense of sight.
How can one bulb use less energy than another bulb and have the same brightness.
One doesn't waist as much energy in thermal energy
Series or Parallel It has extra loops added so that components are connected separately to the cells
Parallel
Series or Parallel It uses more energy quickly, lamps will continue to stay bright even as more are added in parallel
Parallel
Series or Parallel The sum of the current from each branch should be the same as that flowing through the main circuit
Parallel
Explain gravitational potential energy
A rock on a mountain has stored energy because of its position above the ground and the pull of gravity. This energy is called gravitational potential energy. This is energy it would release if it fell. As the rock falls to the ground, the gravitational potential energy is transferred as kinetic energy.
Series or Parallel The switches can be positioned to control individual lamps
Parallel
Explain sound energy
A vibrating drum and a plucked guitar strung transfer energy to the air as sound. Kinetic energy from the moving air molecules transfers the sound energy to your eardrum/
In a series circuit, the current is ..
Always the same throughout the circuit
What is current measured in?
Amps (A)
How many joules are there in a kilowatt hour - show your working?
Joules in a Kilojoule = 1000 J 1 Watt = 1 Joule per Second, so 1 Kilowatt (kW) = 1000 W Seconds in an hour = 60 mins x 60 seconds = 3600 seconds So 1 Kilowatt hour (kWh) = 1000 W x 3600 seconds So 1 Kilowatt hour (kWh) = 3,600,000 J
What do electricity companies charge in?
KILOWATT HOURS =(KWh)
What is a power source?
A cell, battery or power pack
What is an electric current?
A complete path for the current to flow in.
Name all 9 types of energy
Kinetic sound light thermal chemical electrical gravitational pull elastic potential nuclear
How do you measure current?
A device called an ammeter is used. you connect the current flowing through a component in a circuit, you must connect the ammeter in series with it
A positive and negative charge ...
Attract
Why would a jumper and shirt make a crackle noise?
Because it is caused by tiny electric charges on your clothes. This is static electricity. Jumper and shirt electrically charge as they rub together and then negative electric charges jump from one to the other. This makes sparks which crackle
What does a closed switch do?
Completes the circuit so current can flow
A shower has a power of 10 kWh and is used for 1 hour every day. How much would it cost them to use the shower if the cost per kWh is 10p?
Cost = 10 kWh x 10p Cost = 100p = £1 per day to use the shower
What does an open switch do?
Creates a break, or gap, in the circuit to stop current flowing
Electricity is just one of the many different forms of ..
Energy
True or False In a Sankey Diagram, the wasted energy comes out straight forward and the energy we want comes down
False - It is the other way around
What does a lamp (or bulb) do?
Glows when the current flows through it
What do watts tell you?
How quickly they transfer energy
Explain Elastic Potential Energy (Sprain Energy)
If you stretch a rubber band or a spring energy is stored in it until you let go of it. If you fire a bow and arrow, you are using elastic potential energy. The stored energy in the string of the bow is transferred into the kinetic energy of the arrow.
What is a cell?
It provides energy to push the current around the circuit
What is renewable energy?
Renewable energy resources can be replaced, and will not run out.
A negative and negative charge ...
Repel
A positive and positive charge ...
Repel
Series or Parallel All the components are connected alongside one another
Series
Series or Parallel More bulbs in a ... will decrease the current because the bulbs provide more resistance against the flow of current
Series
Series or Parallel The circuit must be complete for the current to flow, switches provide a break in the circuit so stopping the flow of all current
Series
Series or Parallel The current is the same at every point
Series
Name 5 renewable energy sources
Solar energy Wave energy Wind energy Geothermal Tidal
Explain Chemical Energy
Some chemical reactions release energy. For example, when an explosive goes off, chemical energy stored in it is transferred to the surroundings as thermal energy, sound energy and kinetic energy.
In terms of energy, why would some microwaves cook with more joules than others if they use the same amount of amps
Some may waste some energy in light or sound and therefore, some have more joules as heat than others so it would cook quicker.
For an electric current to flow, which two things must you have?
Something to make the electricity flow, such as a battery or power pack A complete path for the current to flow in.
how do you make an experiment more reliable?
Test your data several times
In terms of energy, explain battery circuits with a lamp
The battery is a store of chemical energy. The energy is transferred by electricity to the lamp, which transfers the energy to the surroundings by light. These are useful energy transfers - we use lamps to heat up our room. But there are also energy transfers that are not useful to us. In this example, the lamp also transfers energy to the surroundings by heating. This meas that some energy is wasted.
If you add an extra lamp to a parallel circuit, what will happen?
The battery will run out quicker but the lamps will not become dimmer
In a series circuit, what happens if a lamp breaks
The current is broken so no charge will flow through the circuit.
What is the 'Conservation of Energy'
The idea that energy can be changed from one of its many different forms to another but it can't be made or destroyed.
If you add an extra lamp to a series circuit, what will happen?
The lamps will become dimmer
What is current?
The measure of how much electric charge flows through the circuit.
What is potential difference?
The measure of the difference in electrical energy between two parts of a circuit. The bigger the difference in energy, the bigger the potential difference.
For a series circuit, if you have two bulbs and a battery, what should the potential difference of the battery be the same as?
The potential difference of each bulb added together
Explain briefly the Van de Graff generator about how it creates static electricity
The sphere becomes positively charges and the base becomes negatively charged and as these charges build up and build up until they are allowed to "re balance" themselves by allowing the negative charges to flow back towards the positive charged sphere. these non moving charges are what makes 'static eletricity'
What is the difference between how we connect a voltmeter to an ammeter?
The voltmeter connects to two parts (parallel) but an ammeter connect to on (series)
Explain thermal energy
Thermal energy is another name for heat energy. A cup of hot tea has thermal energy in the form of kinetic energy from its particles. Some of this energy is transferred to the particles in cold milk, which you pour in to make the tea cooler
What is a Sankey Diagram
These are another form of Energy Transfer Diagram but involve number. Sankey diagrams summarise all the energy transfers taking place in a process. The thicker the line or arrow, the greater the amount of energy involved. This Sankey diagram for the lamp shows that it transfers most of the energy by heating, rather than by light:
Explain Nuclear energy
This type of energy is found in atoms. The sun transfers the nuclear energy it makes in its center (the core) into heat and light energy - which is vital for life here on Earth. We also have nuclear power stations - but they make nuclear energy in a different way to the sun.
True or False Is the thickness of the input of the Sankey Diagram, always the same as the output
True - because we say that the energy has been conserved. Energy is always conserved, it is never "lost" or "wasted", although some energy transfers are useful and some are not.
What is a battery?
Two or more cells
What is potential difference other whys known as?
Voltage
What is potential difference measured in?
Volts (v)
What do electrical devices have a power rating in?
Watts (w)
What happens if you put your hands on a Van de Graff generator?
When you put your hands on the surface of the dome, your hair stands up because it is given the positive charges from the surface. Each strand of hair is positively charged and the same charges repel. Your hair standing on end is basically each strand trying to get as far away as possible from the others.
What materials can you make static electricity from?
When you rub two different materials against each other, they become electrically charged. This only works for electrically insulated objects and not with materials like metals, which conduct. The materials gain an equal amount of charge but the charges are opposite (one material becomes negative while the other becomes positive).
Name 3 different fuels for non renewable enrgy
coal, oil and gas
More cells in a circuit increases the ... because ..
current because there is more energy to push the current around
Power in watts = (equation)
energy (j) / Time (s)
Is energy or power kwh
energy = kwh power = kw
How do you find the work done (j)
force (n) x distance (m)
Work is measured in ...
joules (j)
work done / force (n) = distance (?)
meters!!!!!!
The more cells, the ... current
more
Energy (kWh) = (equation)
power (kw) x time
What is work
sometimes when energy is transferred, we instead say we are doing 'work'. If you lift up a book, we say you are doing work against gravity or if you slide a book along a desk, we say you are doing 'work' against friction
In a Sankey Diagram, the thicker the line or arrow, ....
the greater the amount of energy involved.
The more charge that flows...
the larger the current
If a hair dryer uses 6kWh of eletricity energy how many hours would it be used for if it had a power rating of 2 KW
time = energy / power 6kWh /2 kw = 3 hours
What is a Van de Graff generator for?
to show what static electricity can do
How do you measure potential difference?
you must connect the voltmeter in parallel with the component.