click below
click below
Normal Size Small Size show me how
Current electricty
Science
Question | Answer |
---|---|
Current? | Flow of charge |
Unit of current? | Amps (A) |
Symbol for current? | I |
Instrument for measuring current? | Ammeter |
Voltage? | Difference in electric potential between two points |
Voltage unit? | Volts (v) |
Voltage symbol? | V |
Instrument for measuring voltage? | Voltmeter |
Resistance? | Ability of a substance to reduce current |
Resistance unit? | Ohms (♎️) |
Resistance symbol? | R |
Resistance instrument? | Ohmmeter |
Calculate resistance? | V ----- = R I |
Describe the expierment to detirmine the relationship between current potential diff(voltage) and resistance? | Set up apparatus Set voltage to 1 volt Read current flowing on ammeter Increase voltage to 2 volts Read current again Contine until 10 volts Divide the voltage by current |
What is the result of the expierment stating the relationship of I/V/R | Voltage divided by a current is resistance |
What is the conclusion of the expierment? | V ----=R I |
What kind of line should this expierment show on a graph?what os this called | Straight line because of ohms law |
Ohms law states? | Voltage directly poportional to the current! |
Direct current? | Current that flows in one direction only |
Alternating current? | Current that changes direction(every hunderth of a second) |
Electronic devices? | Are used to control very small currents in computers eg television |
Now draw the symbol for a battery? | Ok |
Draw symbol for bulb | Ok |
Diode symbol | Ok |
Resister symbol | Ok |
Buzzer symbol | Ok |
Switch | Ok |
LED | Ok |
LDR | Ok |
Diode definition? | A device that allows current to flow in one direction only |
Forward biased? | If a current flowing from + to - can pass through |
Reverse biased? | If a current cannot pass through |
Experiment to show the heating effect of a current? | Set up apparatus Place thermometer next to bulb Close switch to the light bulb Result- temperature of bulb increases Conclusion-electric current has a heating effect |
Chemical effect of an electric current? | The electrolises experiment |
Magnetic effect of a current? | Set up apparatus Make sure compas needle facing same direction as wire Close switch for a second Result - compass needle turns Conclusion- electric current has a magnetic effect |
Heating effect in everyday appliences? | Kettle and boilers to heat water or electric fires and fuses |
Chemical effect in everyday appliences? | Making hydrogen |
Magnetic effect in everyday appliences? | Used in scrapyards to lift iron (steel) |
Explanation of the series circuit | So the current has to pass through one bulb to get to the next so in other words they are in a row or sequence Both bulbs do shine with equal brightness but do bot light as brightly as they would do in a parrallel If one bulb goes they all go |
Explanation of parallel | Two bulbs are arranged in parrallel both bulbs shine with equal brightness brighter then series if one bulb goes its fine because the currene can go off to the other bulbs |
Static electricity explanation? | Ocuurs when body has charges that are fixed and cant move caused when two insulating materials rubbed together |
Current electricity? | Ocurs when a body has charges running through it |
Electric charges positive? | Caused by removal of electrons from a substance Rub a perspex cloth with a dry woolen cloth |
Negative electric charges? | Caused by addition of electrons to a substance Rub polythene with dry woolen cloth |
Show expierment to generate electricity? | Comb dry hair Take biro and rub it on wool jumper Hold both near scraps of paper Paper attracted as both things have become charged by rubbing Touch each with wire connected to earth Paper falls off showing eathing a charged body removes its charge |
Demonstrete the force between charged objects? | Charge polythene rod hang it on thread Charge another polythene rod by rubbing,bring it close to the suspended rod Result the suspended rod repelled like charges repel Now charge a perspex rod by rubbing Bring to polythene rod It attracts! |
Test electrical conduction in a vary of materials | Set up apparatus Place material tested between two clips Close switch Result: if bulb lights its a conductor if it doesnt its an insulator |
Name and describe the terminals of a plug | Brown is live Blue is neutral Green yellow is earth |
Fuse ? | Safety device of a circuit If too much. Urrent flows the fuse melts and breaks the circuit cutting off the supply of electricity of the device |
Circuit breakers? | Do same job as fuse but use electromagnesium. Its important to use the right fuse value! |
Fuse everyday application... | Rectifying AC (turning AC to DC) Protect circuits for reverse battery connection |
LED stand for ? | Light emmitting Diode |
Function of the LED | Its a diode that gives out light when a current flows through it |
Does a LED require more or less urrent than a bulb? | Less |
Uses of LED | In latest tv screens and for the numbers on calculaters |
The advantages of a LED to a bulb | Less current Lasts longer Less prone to damage |
LDR stands for? | Light dependent resister |
Definition of the LDR | A resister whos resistance decreases with increasing light intensity |
Everyday examples of the LDR | Light meters Automatic light switches on street lamps |
Expierment to show the measuring of resistance of a LDR | Set up apparatus Measure resistance with lamp off Switch on lamp and measure Move lamp closer and measure Result ..the brighter the light the less of resistance Conclusion...resistance of LDR decreases with light intensity |