Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
51 Cards in this Set
- Front
- Back
|
What is the current?
|
The flow of electrons round a circuit.
|
|
|
What is the voltage?
|
It is the driving force that pushes the current round.
|
|
|
What is resistance?
|
It is anything in the circuit which slows the flow down.
|
|
|
What decides the size of the current?
|
The voltage pushes the current and the resistance slows it down, the size of these two things together decides how big.
|
|
|
What happens if you increase the voltage?
|
Then more current will flow.
|
|
|
What happens if you increase the resistance?
|
Then less current will flow.
|
|
|
What way do electrons flow?
|
The opposite way to the conventional current, it goes from negative to postive.
|
|
|
What kind of current is the mains electricity which we have at home?
|
Alternating current-AC. It constantly changes direction.
|
|
|
What is direct current?
|
DC. The current always flows in the same direction. Cells and batteries supply this current.
|
|
|
What kind of lines are the ac and dc?
|
AC=wiggly, DC=straight
|
|
|
What is the voltage equation?
|
Voltage (volts)=current (amps) x resistance (ohms)
V=I X R |
|
|
What does I stand for?
|
The current.
|
|
|
What is an LDR and what does it depend on?
|
A light-depending resistor, it depends on the light level.
|
|
|
What is a thermistor and what does it depend on?
|
An elecrical resistor, it depends on temperature.
|
|
|
What is useful about electrical appliances?
|
They take in electrical energy and convert it into other forms of energy.
|
|
|
Name an example of converting energy?
|
A light bulb turns electrical energy into light and heat energy.
|
|
|
What is converting energy from one form to another called?
|
The transfer of energy.
|
|
|
What is electrical power?
|
The rate of transfer of electrical energy.
|
|
|
The higher the power of your appliance...
|
the more energy is transferred every second.
|
|
|
What is the power equation?
|
Power(watts)=current(amps)x voltage(volts)
P=IxV |
|
|
What is a kilowatt-hours?
|
A kilowatt-hour is the amount of electrical energy converted by a 1kW appliance left on for 1 hour.
|
|
|
What does it mean if you leave your appliance on for a long time?
|
The higher the power rating and the longer you leave it on, means the more energy it consumes,which makes a greater cost.
|
|
|
What is the units of energy equation?
|
Units of energy(in kWh)=power(in kW)x time(in hours)
|
|
|
What is the other units of energy equation?
|
Cost=number of units x price per unit
|
|
|
What does the ammeter do?
|
It measures the current flowing through the component. It must be placed in a series.
|
|
|
What does the voltmeter do?
|
Measures voltage across the component. Must be placed in parallel around the component.
|
|
|
What is the proper name for voltage?
|
Potential difference.
|
|
|
What is a diode?
|
It is a special device made from semi-conductor material like silicon.
|
|
|
What does the diode do?
|
It only lets current flow freely through it in one direction, there's a high resistance in the reverse direction.
|
|
|
What can the AC be shown on?
|
An oscilloscope screen, the trace on the screen shows the voltage of the supply which changes with time.
|
|
|
What happens to potential difference in series circuits?
|
It's shared between the components. They all equal up to the source voltage, so v=v1+v2+v3
|
|
|
What happens to the current in series circuits?
|
The same current flows through all parts of the circuit. A1=A2
|
|
|
What happens to resistance in series circuits?
|
It all adds up, the bigger resistance of a component the bigger its share of the total P.D. So R=R1+R2+R3
|
|
|
What happens to cell voltages in series circuits?
|
There is a bigger voltage when more cells are in series,two cells of voltage 1.5V are connected, they supply 3V between them.
|
|
|
What happens to potential difference in parallel circuits?
|
All components get the same amount of voltage, so v1=v2=v3.
|
|
|
What happens to current in parallel circuits?
|
It is shared between branches. It splits or rejoins at junctions. A=A1+A2+A3
|
|
|
What happens to resistance in parallel circuits?
|
The current through each component depends on its resistance, the lower the resistance, the bigger the current that'll flow through it.
|
|
|
How are voltmeters and ammeters exceptions in parallel circuits?
|
Ammeters are always connected in series, voltmeters are always connected in parallel with a component.
|
|
|
What do all resistors produce?
|
Heat when a current flows through them.
|
|
|
What does the total energy transferred depend on?
|
How long the appliance is on and its power rating.
|
|
|
What is the energy transfer equation?
|
Energy=power x time
|
|
|
What is the total charge equation?
|
Total charge=current x time
q=ixt |
|
|
What happens when an electrical charge goes through a change in voltage?
|
Then energy is transferred.
|
|
|
What is the energy transferred equation?
|
Energy transformed=charge x potential difference e/qv
|
|
|
What does a fuse contain?
|
A thin wire that heats up and melts if too much current passes through it,so if it is too unsafe it'll blow.
|
|
|
What does a rating of a fuse mean?
|
It is the maximum current that can pass through it without melting the fuse wire. If it isn't correct on an appliance,it can set alight.
|
|
|
What is a circuit breaker?
|
Its an electromagnetic switch that opens and cuts the current off in the current if its greater then a certain value.
|
|
|
What is the live(brown)wire?
|
Its connected directly to the generators of the electrical supply company, carries 230 volts.
|
|
|
What is the neutral(blue)wire?
|
It returns the electricity to the generator after it's passed through the appliance. It doesn't carry any volts.
|
|
|
What is the earth(yellow/green)wire?
|
It acts as a safety device, it usually carries no electricity!
|
|
|
What is an LED?
|
A light-emitting diode, a semiconductor diode that glows when a voltage is applied
|
