Chapter 4 - Electricity Flashcards
What are circuit diagrams
circuit digrams shows how electrical components are connected
what is the S.I unit for current
ampere
what is a smaller unit of current
milliampere ( 1A = 1000 mA )
how can we measure current
we can use a multimeter or an ammeter
what is voltage needed for?
voltage is needed for current to flow
what is the voltage symbol ?
V
what is the S.I unit for voltage
volt
what is a smaller unit of voltage
millivolt ( 1V = 1000 mV )
how can we measure voltage
we can use a multimeter and a voltmeter
What is resistance
resistance opposes the flow of current.
Higher the resistance ….
smaller the current
the symbol for resistance
R
what is the S.I unit for resistance
ohm
is a fixed resistor fixed
yes
is a variable resistor fixed
no. it can be adjusted
when the resistors are connected in series the effective resistance becomes
bigger
when resistors are connected in parallel the effective resistance becomes
smaller
we can measure resistance by using a
multimeter
how many paths can current flow in a series circuit?
one
what are the disadvantages of using series
- All bulbs must be turned on & off at the same time
- when bulb blows, the others blow as well
- it is hard to identify the blown blub
how many paths can current flow in a parallel circuit?
more than one
what are the advantages of using parallel circuits
- each bulb can be turned on and off individually
- when one bulb is blown , the rest will still be light up
- it is easy to find the blown bulb
we must handle electricity with care
true
what happens if we are not careful with electricity
there will be electrical hazards
what are the two common electrical hazards
electric shock and electrical fire
what are the causes of these electrical hazards
- damaged insulation
- overheating of cables
- damp conditions
- poor or loose connections
explain about damaged insulation
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
explain about overheating of cables
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.
explain about damp conditions
damp conditions is when the appliances are touched with wet hands. this can result in electric shock as water is a conductor of electricity
explain about loose connections
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
what are the safety uses of electricity
this are used to protect us against these electrical hazards
examples of the safety uses
- fuse
- earth wire
- circuit breaker
- double insulating wire
what does a fuse do
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
what does a circuit breaker do
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
what does a earth wire do
it prevents and overly large current from flowing
what is double insulating wire
it is 2 layers of insulation
what color is live wire
brown
what color is earth wire
yellow and green
what color is neutral wire
blue
what is electrical power
it is the rate at which electrical energy is converted to other forms of energy
what is the S.I unit for electrical energy
watt ( W )
a bigger unit for electrical energy
kilowatt ( kW )
the energy formula
energy = power × time
what does the label on electrical appliances tells us?
the volatge the appliance should be used with and the power rating of the appliance
an appliance with high power rating can
help us get things done faster
electrical power can be calculated by using power voltage and current the formula is …
Power ( W ) = Volts ( V ) × Current ( I )
