Electricity Flashcards
(23 cards)
Electric circuit
A closed loop that provides a path of transfer for electrical energy. Needs:
- a battery/ source of power
- something to power (lightbulb)/ load
- wires to connect the components/ conducting path
Current
The flow of electrical energy. Made up of electrons moving along the wires. Energy is carried
Ammeter
Measure electric current in part of the circuit in amperes (amps, A)
Voltage
A measurement of the amount of energy
- supplied to the charges by the voltage source
- used by the charges as they pass through a component, measured across a component
Measured with a voltmeter in volts
Energy is applied
Conductors
Will allow an electric current to pass through them. Some metals are better conductors than others. Eg:aluminium, copper, tungsten and nichrome
Resistance
The materials level of resistance determines whether it is a good conducter. Eg: copper has little to no resistance . Energy is dissipated
Insulators
Materials that have a high resistance so they can actually block electric current completely. Eg: wood, rubber, glass, ceramic, plastic
current, voltage and resistance
Current, voltage and resistance are all related to each other. Change one of them and atleast one of the others will change as well.
Current, voltage and resistance egs
Current remains the same, then the voltage will decrease as the resistance increases.
Supply voltage remains the same but the resistance is increased so less current will flow.
Ohms law
The relationship between current, voltage and resistance can be summarised by ohms law.
Voltage = current x resistance
V = IR
I is current
R is resistance
Series circuits
All the components of the circuit are connected up one after the other in a single loop. Not very efficient because if one blows they all blow, can’t have individual switches to control the globes and adding more globes to the circuit reduces their brightness.
Parallel circuits
Has a number of branches, each branch having its own components. The same amount of voltage is applied to each branch so the globes shine at the same brightness. Parallel circuits harder to construct but better. Can be controlled individually with switches, if one globe blows not all go out
Series circuits uses
Not very useful, hard to identify broken globe to replace, usually used in fairy lights
Parallel circuits uses
Harder to construct, more useful eg. In houses
Permanent magnets
Have an invisible force around them called a magnetic field. They have a north and South Pole
Electromagnets
Created by running an electrical current through a coil of wire. Can be made stronger by adding coils or having a steel or iron core inside the coils. Used whenever a magnetic field that can be switched on or off is needed.
Electromagnets egs
Car locks, and electric doors, storing computer data, lifting scrap metal
Demonstrate that electric currents produce magnetic fields
Prac with iron filings moving
Magnetic field produced by a current can …
Interact with another magnetic field (electromagnet or permanent magnet)
Changing the magnetic field can…
Swapping the poles makes a repel and attract action producing movement and causing charges to move, making a current
Explain how a simple generator works
Uses kinetic energy to greater electrical energy. Movement to provide current. Creates power from a mechanical force. Opposite of a motor
Explain how an electrical motor works
Uses magnets alongside coils of wire (electromagnets) to transfer -electrical energy into kinetic energy- . When current is passed through the coil, it experiences force in opposite directions caused by the poles of the magnets on either side , creating movement. Eg: car. Current used to provide movement.
Alternative forms of creating electricity
Chemicals (wet and dry cells), solar energy, wind energy, hydroelectricity, wave power, tidal power (water used to turn a turbine), steam energy
