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Chapter 13 Electrical systems - Coggle Diagram
Chapter 13
Electrical systems
electrical components
wires
cell/battery
switch
bulb
harmful effects
electrical fire
when
multiple plugs
are inserted into the
same socket
,
large
amounts of energy is
drawn
from the
power supply
. this results in
excessive heat
and may cause an electrical fire.
electric shock
if a person gets into contact with an
exposed
wire, the
electric current flows through
the body and results in an electric shock.
safety measures to prevent electricity from harming yourself and others
do not overload power sockets
change/replace worn out wires with new ones
do not touch electrical appliances with wet hands
do not insert objects into the opening of a socket
ways to conserve energy
buy appliances that have energy labels with three or more ticks
switch off water heater after use
switch off lights and fans when not in use
switch off air conditioner after a short while before switching to a fan
power
the amount of electrical energy used for conversion to other forms of energy per unit time
calculating
energy
(kWh)
Energy (
kWh
) = Power (
kW
) x Time (
hours
)
calculating
cost
($)
Cost (
$
) = Energy (
kWh
) x Time (
cost per kWh
)
Q: You have a household appliance with a power consumption of 1500 watts. It was used continuously for 5 hours. If the cost of electricity is $0.12 per kilowatt-hour, what is the total cost of using the appliance?
A: find the kW (
kilowatt
) by converting W (
watt
) into kW.
1000W
=
1kW,
so 1500W = 1.5kW
substitute the values into the formula for finding
kWh
kW x time (in
hours
, convert according if Q gives u minutes) = kWh
1.5 x 5 = 7.5kWh
substitute the values into the formula for finding cost
energy (kWh) x cost per kWh = cost ($)
7.5kWh x $0.12/kWh = $0.9 (cost) ✓
:arrow_double_up: remember to write down two decimal place as value is in $
conversion (
W to kW
)
1,000W = 1 kW
ammeter
measures current flowing through an electric circuit
SI Unit:
ampere (A)
circuit symbol
voltmeter
measures
potential difference
(amount of energy needed to move a unit charge from one point to another in a circuit)
across an electrical component
connected in
parallel
with the circuit
circuit symbol:
SI Unit:
volt (V)
resistors
opposes the electrical current, which is known as electrical resistance (R)
higher
resistance →
decreases
flow of current
lower
resistance →
increase
flow of current
series arrangement
current
decreases
as resistance
increases
as there is only one pathway for current to flow through, thus overall current is higher
parallel arrangement
current
increases
as resistance
decreases
due to more currents, allowing the current to flow through multiple pathways
SI Unit:
ohm (Ω)
types of resistors
fixed resistor
(fixed, non-adjustable electrical resistance)
circuit symbol:
variable resistor
(has a range of electrical resistance, adjustable)
circuit symbol:
