Electrical Systems Flashcards
What are electrical cells
Portable source of electricity
Wat do electrical cells contain
Chemical Potential energy which is converted to electrical energy and then different types of energy
What is an electrical circuit
Path along which electrical currents move, formed by electrical components joined together
What is a closed circuit
Electrical components joined together without any gap creating a complete pathway for electrical current to flow through
What is open circuit
Electrical components joined with a gap between creating incomplete path way for electrical current to flow
What is an electrical current
Flow of electric charges
How to measure electrical current
Ammeter
How to connect ammeter to a circuit
Positive terminal of ammeter to positive terminal of the electrical cell
How does conventional current flow + what does it carry
Charge carriers are positive charges
Flows from positive to negative end of terminal
What is electron flow and what does it carry
Carries electrons
From negative to positive terminal of battery
What is potential difference
Aka voltage
Amount of work done to drive a unit charge through the component
How to measure potential difference
Using voltmeter
How to connect voltmeter
Connect in parallel to appliance
What is electrical resistance
Measurement of how much the component opposed the flow of electrical current
SI unit of resistance and relationship
SI unit: ohm
The higher the electrical resistance, the harder it is for current to flow through causing current flow to be lower
How does high/low resistance affect the bulb?
High resistance
Lesser current flow
Dull bulb
Lower resistance
More current flow
Bright bulb
Do insulators and conductors have electrical resistance? [ tell me about special conductors too ]
Yes
Insulator like rubber plastic = vv high resistance = lesser current flow through
Conductor like copper = low resistance = more current flow through
TAKE NOTE: conductors like tungsten and in chrome are special and have vv high resistance
What is a resistor
Electrical devices managing flow of current through circuit via controlling resistance in circuit
What are fixed resistors
Resistor of known value which cannot be changed
What are variable resistors
Aka rheostats
They vary the resistance in a circuit
Tell me about the arrangement of one resistor in series
In series there is only one pathway for electrical current to flow through so one resistor in series will cause more hindrance and lesser current to flow through making bulb dimmer
Tell me about the arrangement of two resistor in parallel
Parallel circuit have more than one pathway for electrical current to flow through causing lesser hindrance despite 2 resistors letting larger current flow through to shine the bulb brighter
What is a series circuit
Circuit with only one pathway for electrical current to flow trough
If there is a gap circuit will be incomplete due to one pathway only causing circuit unit to become open
What is a parallel circuit
It is a circuit it’s more than one pathway for current to flow through
Allows circuit to still be complete even if one bulb blows due to more than one pathway for electrical current to flow through
What happens when a variable resistor slider is moved to the left
Lesser coils for electrical current to flow through
|
Lesser hindrance to occur
|
Larger electrical current flows through
|
Brighter appliance
What happens when a variable resistor slider is moved to the right
More could for electrical current to flow through
|
More resistance and hindrance
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Smaller electrical current flows through
|
Duller appliance
What is a heating element
Something that can heat up rapidly when an electrical current passes through them
Is nichrome a heating element?
Yes as it has high resistance and can withstand very high temperatures
What is tungsten wire
Used insight bulbs due to high resistance and melting point of 2500.C
What is damaged insulation and its impact
Insulating material that has been worn it causing conducting wires to be exposed
Can cause electrical shocks
Why are overheated cables bad and what are its 2 causes
Bad because it can cause electrical fires
Caused by
1. Overloaded sockets causing unusually large currents to pass through them
2. Us of inappropriately thin wires
Why does electricity love water?
Water contains impurities that create a conducting path for electrical current to flow through. It also has low resistance
What are circuit breakers
- Switch off electrical supply in a circuit when an unusually large current passes through circuit
- Protects appliances form damage/fires
- CONNECTED TO LIVE WIRE
What are fuses?
Shor thin wire which cuts off electrical supply in a circuit when unusually large current threatens to pass but fuse needs to be replaced after it blows
What rating should fuses be
Fuse rating should always be SLIGHTLY HIGHER THAN ELECTRICAL APPLIANCE
Why cant fuse rating be equal to appliance rating
If appliance rating is 5 and fuse rating is 5 the electrical current being passed through the fuse is the maximum it can hold causing fuse to melt a little bit every time current passes before fully melting after a while and blowing
Why cant fuse rating be too high?
It may cause really high current to flow through appliance even if appliance cannot handle it as the fuse can causing appliance to be damaged or fires to occur
What is a live wire
Colour: brown
Connected to high voltage and delivers current to appliance
Fitted to fuse circuit breakers and switches
What is a neutral wire
Colour: blue
Completes circuit by providing return pathway for current
It is always at zero voltage
What are earth wires
Colour: blue and green
Connected to metal casing of appliance to prevent user from shocks
Low resistance
Sends unusually large currents to the ground instead of person
What is special about a three pin plug
- has a cartridge fuse to protect appliance during electrical fault
- earth wire protects user from electrical shocks in event of electrical faults which turn appliance live
What is special about double insulation
It has NO EARTH WIRE
Double layer of insulating materials which protects conducting wires and users from electrical shocks
What is the power of an appliance?
Amount of electrical energy used for conversion to other forms of energy per unit time
SI unit of electricity
Watt
1000W = 1KW [ kilowatt ]
How is using a more energy efficient appliance good?
More energy efficient = reduced electrical consumption
