Electricity

Question 1

insulator

Answer 1

an object that does not readily conduct heat or electricity

Question 2

charging of insulators

Answer 2

friction- when 2 insulators are rubbed together one of the materials gains electrons (becomes +tive charge) and the other loses electrons (becomes -tive charge)
objects of the same charge repel
objects of opposite charges attract

Question 3

uses of electrostatics

Answer 3

paint spraying

dust extraction

Question 4

dangers of electrostatics

Answer 4

objects can become earthed- dangerous build up of static charge which can cause sparks

Question 5

formula for current

Answer 5

charge (Q)/ time (T)

Question 6

define current

Answer 6

the RATE of flow of charge- charge carriers are generally electrons, measured in amps (A)

Question 7

define coulomb

Answer 7

amount of charge that passes in 1 second when the current = 1A

Question 8

define potential difference

Answer 8

the energy converted per unit charge moved (out circuit) measured in volts (V)

Question 9

formula for voltage

Answer 9

energy (W) /charge(Q)

Question 10

define resistance

Answer 10

how difficult it is for current to flow through a component, measured in ohms

Question 11

what is resistance dependent on

Answer 11

length of wire- longer wire = higher resistance
cross sectional area of wire- wider wire= lower resistance
resistivity of wire - dependent on material, wire structure, environmental factors e.g temp

Question 12

series circuit

Answer 12

circuit where the current follows one path

Question 13

parallel circuit

Answer 13

circuit where current splits in more than 2 paths

Question 14

current, voltage and resistance rules

Answer 14

for series: 
Rt=R1+R2
I1=I2=I3
Voltage splits but is dependent on the components
for parallel:
v1=v2=v3
current splits but depends on components
total resistance is less than the branch w/ smallest resistance

Question 15

formula for power

Answer 15

currentxvoltage

Question 16

electromagnetic induction

Answer 16

magnet rotates in coil of wire
causes change in magnetic field
induces voltage creating AC

Question 17

why is electromagnetic induction ac

Answer 17

as every half turn the magnet takes voltage reverses

Question 18

4 ways to increase voltage induced in electromagnetic induction

Answer 18

add iron core in coil
increase strength of magnetic field ie stronger magnet
increase rate of rotation
increase number of turns in coil

Question 19

what is a transformer?

Answer 19

device used to change the pd
step up- increases pd
step down- decreases pd

Question 20

step up and down transformers

Answer 20

step up- more turns on secondary coil

step down- more turns on primary

Question 21

what does 100% efficiency mean

Answer 21

complete transfer of electrical power

Question 22

how to generators produce electricity

Answer 22

electromagnetic induction