electricity

Question 1

which particle in an atom can freely move around

Answer 1

delocalised electrons

Question 2

what is static electricity

Answer 2

buildup of charge in 1 location caused by 2 insulators

Question 3

like charges __ unlike charges ___

Answer 3

repel,attract

Question 4

when are electrons transfered

Answer 4

when objects become charged

Question 5

what happens when 2 insulators are charged by friction

Answer 5

one ends up negatively charged due to having elections being lost and the other becomes negatively charged because excess electrons were transfered

Question 6

what happens when a negatively charged insulator touches another insulators

Answer 6

the negatively charged insulator attracts the protons in the normal insulator when the charged insulator discharges its electrons to the normal insulator

Question 7

how does lightning happen

Answer 7

in storms 2 clouds rub against eachother which causes friction between the water vapours,then one of the clouds becomes charged and is attracted to the positive ground which causes it to discharge

Question 8

whats the unit and definition for current

Answer 8

• rate of flow charge
  measured in amperes (A)

Question 9

what does I=Q/T mean

Answer 9

current in A is equal to charge in columbs divided by time in seconds

Question 10

whats the unit and definition for voltage

Answer 10

-energy transfered per columb of charge (basically the force applied to move electrons)
-volts

Question 11

whats the unit and definition for resistance

Answer 11

-anything that opposes the electric current
-ohms (Ω)

Question 12

whats the difference between cells and batteries

Answer 12

a cell is a single unit which converts chemical to electical energy
battery is a collection of cells

Question 13

whats the symbol of a fuse what is its function

Answer 13

its like a resistor with a line drawn through the middle , its designed to melt and break when the current exceeds its limit

Question 14

what is meant by LED and LDR

Answer 14

-LED (play button and arrows go outwards in symbol) is light emitting diode, it emits light while allowing current to flow in only 1 direction
-LDR (resistor with arrows pointing inwards) is light dependent resistor

Question 15

which way are ammeters connected and what do the measure

Answer 15

connect in series and measure current

Question 16

which way are voltmeters connected and what do the measure

Answer 16

connect in parallel and measure voltage

Question 17

whats the relationship between voltage,energy transfered and charge

Answer 17

V=E/Q

Question 18

what happens in parallel circuits

Answer 18

current is divided and the voltage stays the same

Question 19

what happens in series circuits

Answer 19

voltage is divided and current stays the same

Question 20

whats happens when resistance increases

Answer 20

voltage and current will also increase to overcome it

Question 21

what is ohms law

Answer 21

current is proportional to voltage at constant temperature and resistance

Question 22

what happens if temperature increases

Answer 22

resistance increases due to particles vibrating more frequently with more kinetic energy

Question 23

what are the iv characteristics of a fixed resistor

Answer 23

-ohomic conductor
-straight line and linear graph

Question 24

if y=current and x=voltage then

Answer 24

the steepest line is the highest resistance

Question 25

if y=voltage and x=current then

Answer 25

the shallowest line is the highest resistance

Question 26

how do fillament lamps work

Answer 26

the wires heat up then electric energy is transferred to infrared rays that emit light

Question 27

whatre the iv characteristics of a filament lamp

Answer 27

-nonohomic conductor
-as current increases theres more of an heating effect so the wire heats up more causing increases resistance due to electrons coliding more often
-line plateus due to max voltage

Question 28

what are the iv characteristics of a diode

Answer 28

at negative end theres super high resistance and at the start of positive end the voltage and current are trying to overcome resistance then finally the resistance decreases

Question 29

what are the different variables for the required practical

Answer 29

controlled; resistor (filament lamp/diode/fixed resistor)
dependant(measured): current
independent(changes): voltage

Question 30

whats the procedure for the required Practical

Answer 30

• connect any resistor filament lamp or diode to a series circuit that looks like this (draw diagram with variable power supply,ammeter,volmeter connected with lamp in parallel)
  -keep resistance constant and change voltage using variable power supply
  -flip batteries to measure both polarities
  -plot iv graph and calculate resistance
  -(for each component explain the characteristics theyll get when they plot it)

Question 31

when does resistance increase in a thermistor

Answer 31

when its cold due to it being a negative temp coefficient so it acts opposite to normal resistor .

Question 32

in thermistor, as temp increases, resistance ___

Answer 32

decreases

Question 33

in LDRs as light increases,resistance __

Answer 33

decreases

Question 34

what happens in ldr when its dark

Answer 34

very high resistance so more current is neederd to overcome it

Question 35

how do LDR sensors work when its dark

Answer 35

the resistance is very high so more voltage and current is needed to overcome it. since lamp is connected in parallel to ldr the voltage is shared so the voltage increases in both ldr and lamp and more light is emitted

Question 36

what happens to LDR sensors when its light

Answer 36

the resistance decreases so less voltage is needed to overcome it. since in lamp is connected in parallel to ldr voltage is shared, not much voltage is transfered through both the lamp and ldr so little light is emitted

Question 37

why will a decrease in light intensity of LDR decrease ammeter readings

Answer 37

because resistance will increase as theyre inversely proportional

Question 38

can static electricity happen between a insulator and conductor?

Answer 38

no because they wont transfer energy to eachother

Question 39

why will resistance of metal filament increase as voltage increases

Answer 39

since the filament is metal it contains free electrons so when current flows through so does voltage and the temp increases which causes atoms to virbrate faster and colide more frequently

Question 40

voltage= current X _____

Answer 40

resistance

Question 41

describe how a student would use __ circuit to determine resistance in resistor r

Answer 41

switch on the battery and close the switch then record initial values of both ammeter and voltmeter. adjust the variable resistor to change the current then take the new reading. plot an iv graph and find the gradient R=V/I

Question 42

what is the unit of power

Answer 42

watts (W)