Chapter 4 - Electricity

Question 1

What are circuit diagrams

Answer 1

circuit digrams shows how electrical components are connected

Question 2

what is the S.I unit for current

Answer 2

ampere

Question 3

what is a smaller unit of current

Answer 3

milliampere ( 1A = 1000 mA )

Question 4

how can we measure current

Answer 4

we can use a multimeter or an ammeter

Question 5

what is voltage needed for?

Answer 5

voltage is needed for current to flow

Question 6

what is the voltage symbol ?

Answer 6

V

Question 7

what is the S.I unit for voltage

Answer 7

volt

Question 8

what is a smaller unit of voltage

Answer 8

millivolt ( 1V = 1000 mV )

Question 9

how can we measure voltage

Answer 9

we can use a multimeter and a voltmeter

Question 10

What is resistance

Answer 10

resistance opposes the flow of current.

Question 11

Higher the resistance ….

Answer 11

smaller the current

Question 12

the symbol for resistance

Answer 12

R

Question 13

what is the S.I unit for resistance

Answer 13

ohm

Question 14

is a fixed resistor fixed

Answer 14

yes

Question 15

is a variable resistor fixed

Answer 15

no. it can be adjusted

Question 16

when the resistors are connected in series the effective resistance becomes

Answer 16

bigger

Question 17

when resistors are connected in parallel the effective resistance becomes

Answer 17

smaller

Question 18

we can measure resistance by using a

Answer 18

multimeter

Question 19

how many paths can current flow in a series circuit?

Answer 19

one

Question 20

what are the disadvantages of using series

Answer 20

1. All bulbs must be turned on & off at the same time
2. when bulb blows, the others blow as well
3. it is hard to identify the blown blub

Question 21

how many paths can current flow in a parallel circuit?

Answer 21

more than one

Question 22

what are the advantages of using parallel circuits

Answer 22

1. each bulb can be turned on and off individually
2. when one bulb is blown , the rest will still be light up
3. it is easy to find the blown bulb

Question 23

we must handle electricity with care

Answer 23

true

Question 24

what happens if we are not careful with electricity

Answer 24

there will be electrical hazards

Question 25

what are the two common electrical hazards

Answer 25

electric shock and electrical fire

Question 26

what are the causes of these electrical hazards

Answer 26

1. damaged insulation 2. overheating of cables 3. damp conditions 4. poor or loose connections

Question 27

explain about damaged insulation

Answer 27

it is when the layer of insulation is used to cover the wires is damaged and when the bare wires are shown. whoever touches it will be electrocuted

Question 28

explain about overheating of cables

Answer 28

it is when too many appliances are plugged into a single main socket and the current flowing out will become large. this can result in electrical fire.

Question 29

explain about damp conditions

Answer 29

damp conditions is when the appliances are touched with wet hands. this can result in electric shock as water is a conductor of electricity

Question 30

explain about loose connections

Answer 30

this happens when exposed wires are touching each other. this can cause electrical fire and sparks can be produced at the points of loose connections

Question 31

what are the safety uses of electricity

Answer 31

this are used to protect us against these electrical hazards

Question 32

examples of the safety uses

Answer 32

1. fuse 2. earth wire 3. circuit breaker 4. double insulating wire

Question 33

what does a fuse do

Answer 33

a fuse is a safety device that prevents and overly large current from flowing. it is made up of a thin piece of copper in a case

Question 34

what does a circuit breaker do

Answer 34

it is a rectangular box that is that is located near the entrance in all houses. it also prevents and overly large current from flowing

Question 35

what does a earth wire do

Answer 35

it prevents and overly large current from flowing

Question 36

what is double insulating wire

Answer 36

it is 2 layers of insulation

Question 37

what color is live wire

Answer 37

brown

Question 38

what color is earth wire

Answer 38

yellow and green

Question 39

what color is neutral wire

Answer 39

blue

Question 40

what is electrical power

Answer 40

it is the rate at which electrical energy is converted to other forms of energy

Question 41

what is the S.I unit for electrical energy

Answer 41

watt ( W )

Question 42

a bigger unit for electrical energy

Answer 42

kilowatt ( kW )

Question 43

the energy formula

Answer 43

energy = power × time

Question 44

what does the label on electrical appliances tells us?

Answer 44

the volatge the appliance should be used with and the power rating of the appliance

Question 45

an appliance with high power rating can

Answer 45

help us get things done faster

Question 46

electrical power can be calculated by using power voltage and current the formula is ...

Answer 46

Power ( W ) = Volts ( V ) × Current ( I )