Current Electricity - Gr.9 Flashcards
Electrical Power
What is electrical power, its symbol and unit?
Electrical power is the rate of change of elctrical energy. Its symbol is P and unit is joules (J)/ Watt (W).
Electrical Power
How do you turn 100w to Kh?
Divide by 1000 (0.1)
Calculate the Efficiency:
A lightblub uses 103J and produces 40J.
(output/input)100
(40/103)100
0.388(100)
38.8
Calculate cost of Electricity:
75W
Electricity costs 9.5 cents/kWh
how much would it cost for 1 year for 4 hr/day.
- 75/1000=0.075kW
- 4(365)= 1460h
- 1460x0.075x9.5=1040 cents
- 1040/100= $10.40
Types of Energy
What is:
Kinetic Energy
Chemical Energy
Nuclear Energy
All forms of energy can be converted into other forms
- The energy of motion
- engory stored in the bonds of atoms and molecules
- energy stored in the nucleas of an atom
What are renewable/non-renewable sources?
Renewable energy sources can be replaced or restocked within humanlife.
Non-renewable cannot be replaced or restocked within human life.
Eg. water and wind. fossil feuls and Uranium
What are the three factors to consider when assseing an energy source?
- Impact on eco-systems
- Impact on society
- Economic-consideration (Technology available, efficent, cost-effictive etc.)
What is a:
Curcuit breaker (rainbow)
Variable resistor (rheostat) (arrow going through a resistor)
Ground connection (down arrow)
- Like fuse, but can be reset.
- A resistor but controlable
- connects to the ground to allow discharge.
Curcuit boards
When electrons finish going through a lightbulb, do they have to return back to the battery?
Curcuit boards
If a switch is open, can electrons flow?
No.
There must be a close curcuit (complete path) for electrons to travel.
Curcuit boards
What is an open curcuit?
When there is a break/incomplete path in the circuit.
Ex. open switch blocks the path for electrons
Circuit boards
What does a complete/controlled electrical circuit have?
- Energy source
- Load
- connecting wires
- Switch
Electrical circuits
What is a short Circuit?
A circuit that has a path that lets electrons flow, but no load.
It is very dangerous
What is Current?
The flow of electrons
Electrical circuits
What is a
Dry Cell
Wet Cell
Primary Cell
Secondary Cell
Fuel Cell
Solar
- Contains Paste electrolyte
- Contains Liquid electrolyte
- Cannot be recharged
- Can be recharged
- Converts chemical reactions of feul to energy
- Converts Sunlight to energy
Electrical circuits
Electrons travel in big groups called a _____.
Coulomb
Electrical circuits
What is Electric Current, symbol and unit of measurement?
Measures the rate at which electrons are flowing in a circuit.
I and Ampheres (A)
Electrical circuits
What device can be used to measure current?
Ammeter.
What is the symbol/unit for Current, Charge and Time?
- I and amperes (A)
- Q and Coulomb (c)
- t and seconds (s)
If 240c of charge passes a point in a circuit in 300s what is the current through that point in the circuit?
Q/t=I
240/300=0.8A
What is Electrical Resistance?
A property of a substance that hinders/resists electric current and convertys electrical energy to other forms of energy.
Like a speedbimp
What is a resistor?
A resistor is a device used to decrease the current.
The higher the resistance, the slower the current.
What is the symbol and unit of measurement for resistance?
(R)=Ohms (Ω)
A technician measured the current as 4.7A.The total potential difference is 12V. What is the resistance?
Ohms Law: R=V/I
- 12/4.7A
- R=25.53 Ω
- R=26Ω
What are the factors affecting the resistance of wires?
- The type of material (some have less resistance than others)
- The length (shorter wires are faster)
- The thickness (thicker wires are faster)
- Temperature (cold has less resistance than hot.)
How is the Current in a series circuit? Parallel?
In a series, the current is the same all throughout different points.
In a parallel, the total current at the source is the sum of all the current.
How is the potential difference in a series circuit? Parallel?
In a series, the potential difference at the load is the total sum of the potential difference of all voltage.
In a parallel, the voltage at the source is the same all throughout different points.
How is the resistance in a series circuit?
In a series, the resistance at the source is the total sum of all the resistance.
Electrical energy
How do you change from W to kW?
Divide by 1000 (ex. 250W= 0.25kW).
What is electrical energy?
Electrical energy is the rate of energy be passed though. its energy used for powering things.
What are two differences and similarities between a parallel and a series circuit?
- They both need a load, wires and source
- voltmeters still have to be connected in parallel.
1.one circuit has only one path
2.current is equal all throughout in a series circuit.
What happens to a lightbulb when more and more are added in series?
The more loads there are, the dimmer each bulb will be. It is because the voltage has to be spread accross more loads.
Explain a method of generating electricity. Name an advantage and disadvantage.
- Wind energy. It is when wind spins a turbine which causes teh turbine to spin the electric generator creating wind energy.
- Wind energy is renewable
- Too loud and ruins scenery
How would decreasing the diameter of a conductor affect its resistance?
It will increase resistance because the thinner a wire is, the less space for electrons to travel.
How would extending the length of a conductor affect its resistance?
It will increase in resistance because the longer the cord, the more resistance electrons will travel through and more energy will be lost.
How will switching from silver to copper wire affect its resistance.
The type of material can impact the resistance. Since copper is a better conductor, the resistance will decrease.
