Electricity Flashcards
Current
An electric current is the rate of flow of charge through a conductor.
Voltage
Voltage is a measure of the amount of energy which the charge is carrying.
Q
Charge (C)
E
Energy
V
Voltage
I –
Current (A)
T
Time (s)
E
Energy (J)
V
Voltage (V)
R
Resistance (Ω)
P
Power (W)
learn symbols of electric circuits
took a screenshot
What happens when you disconnect one of the Lamps in series and paralllel?
In series circuits when one bulb is broken or does not work anymore it mean the whole circuit will not work anymore because there is no more current going through
In parallel all the other lamps still work because the current only stopped going through the lamp you unscrewed, the other lamps in the circuit are still working because the current in still going through those lamps(loops)
What happens to the brightness of the lamps as more are added in parallel?
as more lamps are added the brightness of the lamps stay the same
advantages and disadvantages of series
Require fewer wires to construct(cheaper)
If a fault occurs the whole circuit stops working
advantages and disadvantages of parallel
Each loop can be controlled separately
If one loop breaks the others keep working
Circuits are more complicated to construct
resistor
Current is directly proportional to Voltage
Resistance is constant as power supply varies
filament lamp
The current/voltage graph is a curve
Resistance increases as the voltage increases and the lamp gets brighter and hotter. Atoms and ions in metal vibrate more and make it harder for the electrons to flow through
LED (diode)
Current/Voltage graph is a curve
Resistance decreases as the voltage increases
It only allows current to flow in one direction
How would you plot a voltage/current for a filament lamp?
- The quantities to be measured were current and voltage
- The apparatus used were voltmeter, ammeter, filament lamp, power supply and wires.
- The voltmeter was measured in parallel to the filament lamp while the the ammeter, filament lamp and power supply were in series
- In this experiment we don’t need to do repeats because they are not generally useful for the results.
- To insure accuracy make sure the readings are stable and try to pick the value in the middle if the reading are varying. Make sure there are no loose wires and all are fimly put in.
- There are no equation in this experiment
- To ensure safety ensure that the power supply does not surpass 12Volts, always have a low voltage power supply.
Light Dependent Resistor
(LDR)
-The resistance changes with light.
-As the light gets brighter the resistance of the LDR decreases.
Thermistor
-Resistance changes with temperature.
-As the temperature increases the resistance of the Thermistor decreases..
How to pick fuse?
When picking a fuse for a device we should always pick the SMALLEST one which will NOT melt.
Fuse
it is a small wire that will break and not allow current to flow if current gets too high and might damage the human
Earth wire
When a fault occures the hearting element of the kettle touches the metal case. The kettle is now life and can electrocute a person if they don’t have a earth wire.
If you do have a earth wire you will not be electrocuted. The current always chooses path with least resistance. So to the route to the ground the current will prefer to take the route through the earth wire rather then the person(keeping the safe). If this happens the fuse blows
2 main dangers of electricity
-someone can be electrocuted
-cause overheating, you can be burned or something can catch fire
Insulator
insulator are used as a way to protect you from touching objects that may become live.
Double insulator is when the appliance are insulated in plastic
Direct Current – d.c.
A d.c. supply (such as a battery or cell) produces a flow of charge through a circuit in one direction only
Alternating Current – a.c.
An a.c. supply (such as the Mains) produces a flow of charge that regularly reverses its direction through a circuit
How does a ballon stick to the wall?
The balloon is negatively charged whilst the wall is positively charged (it has the same number of positive and negative charges). The negatively charged balloon repuls the negative charges in the wall away. The front face of the wall now has a net positive charge. This attracts the negative balloon.
How does a paper stick to a comb?
The scraps of paper are electrically neutral. The positively charged comb attracts the negative charges in the paper. The side of the paper nearest the comb now has a net negative charge. The positive and negative charges attract and the paper sticks to the comb.
