Electricity
Electricity is the flow of elecrtric charges
Secondary energy source(primary sources is fossil fuels, solar enrgy, wind or water)
electric cells, electric generators and solar cells-devices used to convert primary energy to source to electricity
Electric generators
large amount of electricity to households and industries
KInetic E.--Electrical E. Or Potential E.-- Electric E.
Windmills or wind turbines, power stations
Electric cells
Small amount of electricity to portable electrical devices
Chemical E.--Electrical E.
Dry cells, lithium cells, lead acid accumulators
Solar cells
Supply electricity to specific devices such as statelites or calculators
Solar E.--Electrical E.
Solar panels in calculators and photovoltaics
Electricity can be transformed into other types of energy such as light, heat and chemical energy or mechanical energy through energy converters
Components that can be found in an electrical circuit
Power source
Produce electricity
Battery
Conductors
Provide path for electricity to flow
Copper wire
Loads
Convert electcrical energy to other forms of energy to perform work
Electrical appliances, lamps, ovens
Control devices
Continue and (Dis-) flow of electricity
Switches, relays
Protective devices
Stop flow of electricity when becomes dangerous
Fuses, circuit breakers
A circuit diagram is a drawing to represent a circuit using electrical symbols
Open Circuit
Also an incomplete circuit
Switch open
break in circuit
No electricity flows
caused by faulty working devices/break in protective devices
eg. light bulb does not light up
Closed Circuit
Complete circuit
switch closed
circuit is complete
Electricity flows non-stop
eg. light bulb lights up
Three categories
Conductors
Materials that allows electricity to pass through them easily
Copper, silver, other metals
Copper used as conducting wire
Insulators
Materials that do not allow electricity to pass through them.
Plastic, rubber, glass, fibres, wood
Plastic or rubber is used as protective layers on wires
Resistors
Materials that limit or regulate amount of electricity passing through them, converts electrical energy into other forms of energy
Nichrome-made of nickel and chromium
Nichrome is used as the heating element to convert electrical energy into heat energy
Types of circuits
Series circuit
Loads arranged one after another
single loop or branch
Only one path for flow of electricty
plus- simple to build
minus-resistance increase when more loads added
minus 2-one load damaged, affects the functionality of other loads
Parallel circuit
Loads arranged in multiple loops or branches
more than 1 path for electricity to flow through
plus-more loops added total resistance decreases
plus 2- loads damaged, it does not affect the functionality of the other loops
paralell circuit is used in the connectionof circuits in households
Current
It is the rate of flow of electric charges
SI unit-ampere(A), symbol of l
supplied by power source in the circuit such as electric cells
Power source two terminals-positive and negative
energy supplied by cells forces electrons to move out from negative terminal of source and flow in the circuit
electrons flow back to positve terminal of source
energy of source used up eventually not the electrons
flow of electrons from negative terminal to positve teminal of a power source is called electron flow
Conventional current model, used to indicate direction of electric current in circuit, flows from positive to negative terminal of the power source in a circuit
Measuring electric current
Ammeter is an instrument used to measure electric current
To measure the lectric current in a circuit
Ammeter connected in series with other electrical components when measuring electrical current in a circuit
Negative terminal of ammeter is connected to the negative terminal of power source
Positive terminal of the ammeter is connected to the positive terminal of the power
Type of circuit
Series
Parallel
electric current is the same at every point
single loop, other components are the same or different
each loop has a specific amount of electric current flowing in it
Total current,l, in the electric
the total currebt-sum of current in all loops
Potential difference
energy is required to move electric charges from one point to another of elctrical components
Potential difference, electrical energy required to move a unit electric charge across the two points of an electrical component. Potential difference is voltage
Measuring potential difference
A voltmeter is used to measure the potential difference across the two points of electrical components
The voltmeter must be connected in parallel across the elctrical components
Voltmeter is connected in parallel with the resistors to measure the potential diference across the two points of it
Resistance
Resistance, property of an electrical component that opposes slow of electrical charges through it. Measure how difficult the electrical current(takes) to pass through and electrical component
Resistance(R)=Voltage(V)/Current(l)