Transcript Force, Energy & Communication

Force, Energy &
Communication
Lesson 5
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
REMEMBER!
Charge passed
=
Current X
Time
(amperes)
(seconds)
(coulombs)
Q = It
Electrical power
(watts)
=
Current
(amps)
P = IV
X
Voltage
(volts)
Cost of Electricity
cost of electricity = power (kW) x time (h)
x cost of 1kWh
Copy and complete this table
Appliance Rating
(kW)
Time (h) Energy
(kWh)
Storage
heater
2
4
Cooker
7
2
1-bar electric
fire
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
2x4=8
Cost at 10p
per unit
8 x 10 = 80p
Copy and complete this table
Appliance Rating
(kW)
Time (h) Energy
(kWh)
Cost at 10p
per unit
Storage
heater
2
4
2x4=8
8 x 10 = 80p
Cooker
7
2
7x2 = 14
14x10 = 140p
1-bar electric
fire
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
Copy and complete the following summary using these words
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joules
energy
twice
energy
voltage
previous
subtract
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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
a label on an appliance says “1kWh” it
means it will use ………….. at the rate of
1000 …………… per second . A “2kW”
appliance uses energy …………….. as
quickly as a “1kW” appliance.
Electromagnetic induction
The magnetic force on a current

When a current flows
through a wire held
between two poles of a
magnet there is an
upwards force on it.
The magnetic force on a current
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The force becomes stronger if…
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the current is increased
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a stronger magnet is used
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there is a greater length of wire in the
magnetic field
The magnetic force on a current
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The force isn’t always
upwards .
It depends on the
current and the field
directions.
If the wire is in line with
the field, there isn’t any
force at all.
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