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Force, Energy &Communication
Lesson 5
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Lesson Objectives
To consolidate our knowledge on electrical
power from last lesson
To look at the costing for electricity
To investigate the magnetic effect of a
current
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REMEMBER!
Charge passed = Current X Time
(coulombs) (amperes) (seconds)
Q = I t
Electrical power = Current X Voltage
(watts) (amps) (volts)
P = I V
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Cost of Electricity
cost of electricity = power (kW) x time (h)
x cost of 1kWh
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Copy and complete this tableAppliance Rating
(kW)
Time (h) Energy
(kWh)
Cost at 10p
per unitStorage heater 2 4 2 x 4 = 8 8 x 10 = 80p
Cooker 7 2
1-bar electricfire
1 1.5
Kettle 2 0.1
Iron 1 1.2
Fridge 0.12 24.0
Lamp 0.06 6.0
CD player 0.012 2.0
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Copy and complete this tableAppliance Rating
(kW)
Time (h) Energy
(kWh)
Cost at 10p
per unitStorage heater 2 4 2 x 4 = 8 8 x 10 = 80p
Cooker 7 2 7x2 = 14 14x10 = 140p
1-bar electricfire
1 1.5 1x1.5 = 1.5 1.5 x 10 = 15p
Kettle 2 0.1 2x0.1 = 0.2 0.2 x 10 = 2p
Iron 1 1.2 1 x 1.2 = 1.2 1.2 x 10 = 12p
Fridge 0.12 24.0 0.12x24 = 2.88 2.88 x 10 = 28p
Lamp 0.06 6.0 0.06x6.0= 0.36 0.36 x 10 = 3.6p
CD player 0.012 2.0 0.012x2= 0.024 0.024 x 10 = 0.24p
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Copy and complete the following summary usingthese words
joules
energy
twice
energy voltage
previous
subtract
To find the number of units used on an
electricity bill, .. the
meter reading from the present one. You
pay for the . you have used not
the .. or the current supplied. If alabel on an appliance says 1kWh it
means it will use .. at the rate of
1000 per second . A 2kW
appliance uses energy .. asquickly as a 1kW appliance.
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Electromagnetic induction
http://bednorzmuller87.phys.cmu.edu/demonstrations/electricityandmagnetism/magneticfields/demo6307.mpg8/3/2019 Magnetic Effect of a Current
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The magnetic force on acurrent When a current flows
through a wire held
between two poles of a
magnet there is anupwards force on it.
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The magnetic force on acurrent The force becomes stronger if
the current is increased
a stronger magnet is used
there is a greater length of wire in the
magnetic field
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The magnetic force on acurrent The force isnt always
upwards .
It depends on the
current and the fielddirections.
If the wire is in line with
the field, there isnt any
force at all.
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Lesson Objectives
To consolidate our knowledge on electrical
power from last lesson
To look at the costing for electricity
To investigate the magnetic effect of a
current
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