chapter 13

Question 1

purpose of cell

Answer 1

energy source to rive electricity in the circuit

Question 2

electric charge

Answer 2

carried by negatively charged electrons that move within the connecting wires

Question 3

wires

Answer 3

allow electric charge to flow through the components

Question 4

electrical device

Answer 4

energy is transferred from the cell to the device

Question 5

electric current

Answer 5

rate at which electric charge flows

Question 6

what causes electric current

Answer 6

movement of electrons in the electrical conductors

Question 7

ammeter

Answer 7

measure current flowing through circuit, ampere (A)

Question 8

how is ammeter connected

Answer 8

series
- - to - of cell
- + tp + of cell

Question 9

potential difference: voltage

Answer 9

amount of energy needed to move a unit charge from one point in a circuit to another

Question 10

how to measure pd/voltage

Answer 10

voltmeter:
volt (V)

Question 11

how to connect voltmeter

Answer 11

parallel
- negative to negative
- positive to positive

Question 12

electrical resistance,R

Answer 12

measure of how much eh component opposes the flow of electric current

Question 13

electric insulator

Answer 13

reisistance is so high that current cannot flow through it

Question 13

electric conductor

Answer 13

low resistance

Question 14

SI unit of electrical resistance

Answer 14

ohm Ω

Question 15

electrical conductors with low resistance

Answer 15

copper silver

Question 16

electrical conductors with higher resistance

Answer 16

tungsten nichrome
- convert electrical energy to other form of energy (light bulb light->heat)

Question 17

types of resistors

Answer 17

• variable
• non-variable

Question 18

variable resistor

Answer 18

range of electrical resistance that can be adjusted

Question 19

non-variable resistor

Answer 19

fixed, non-adjustable electrical resistance

Question 20

what happens when 2 resistors are added in series

Answer 20

• reading on a meter decreases
• bulb is less bright
• decrease in current flowing through circuit, but overall resistance has increased

Question 20

variable resistor application

Answer 20

household appliances to control current in a circuit
- control dimness/brightness of light
- convert electrical energy to light/heat energy

Question 21

what happens when 2 resistors are added in

Answer 21

• there is more than one path fro current to flow
• ammeter reading increases, bulb becomes brighter
• increase in current flowing through ciruit -> resistance decreased

Question 22

useful effects of electricity

Answer 22

chemical effect
heating effect

Question 23

chemical effect of electric current

Answer 23

when electric current in passed through certain chemical solutions/liquids, chemical change take place

Question 24

coating for medical instruments

Answer 24

- repeated cleaning will increase rate of corrosion - electroplating these instrument with a layer of protective metal can minimise damage and lengthen their lifespan - can destroy harmful microorganisms

Question 25

coating for implants

Answer 25

- electroplated - metal can cause allergic reactions and are more likely rejected by the body - coating metal with living tissue can reduce infection and rejection

Question 26

heating effect for electric current

Answer 26

- some electric current converts to heat energy - wire made of a high resistance material, that can withstand high temperatures

Question 27

magnetic effect of an electric current

Answer 27

- when no current, the needle points to north - when current flows, the needle deflects from the position

Question 28

electro magenet

Answer 28

- increase: insert iron core inside the coil fo wire

Question 29

harmful effects of electricity

Answer 29

electrical fire electric shock

Question 30

electric fire

Answer 30

electric circuit is damaged, or multiple plugs are inserted into the same socket - a very large amount of current has to be drawn from the power supply - excessive heat, cause wires to melt and fire

Question 31

electric shock

Answer 31

wires carrying electricity to electrical appliances are insulated with plastic/rubber - protects used from electric chock - when insulating material is worn out, wires are exposed, posing as a potential hazard - water is an electrical conductor which allows current to flow through it

Question 32

safety devices

Answer 32

fuse -circuit breaker

Question 33

fuse

Answer 33

fuse metal when excessive current higher than the fuse rating flows through it - maximum amount of current that can flow through fuse before the wire inside melts

Question 34

1kw is

Answer 34

100w

Question 34

circuit breaker

Answer 34

- when current flow is too large, switch linked to appliance trips and cuts off current, preventing electric chocks