Inspire
physics
Grade 10 ADV
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Using electrical energy
Page 101
Heating a resistor
Current moving through a resistor increases its thermal energy
because flowing electrons bump into the atoms in the resistor
Page 102
Power formula
2
2
P=I R
Current
or
P=
V
R
resistance
Calculating the amount of energy transformed to
thermal energy by a resistor
E=pt
or
2
E=I Rt
or
2
E=
V
R
time
Superconductors
* Is a material with zero resistance .
* Almost all superconductors must be kept at temperature below 100 k .
* The practical uses of superconductors today include MRI magnets.
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Using electrical energy
Page 104
Kilowatt - hour
1 kilowatt hour (kWh) = 1 kilowatt x1 hour
= 1000J s-1 X3600s
6
= 3.6 x 10J
Kilowatt hour ( kWh ) and J are the units of electrical energy
but kilowatt hour is a bigger units. J is the SI units
Electrical energy units
Joule ( J ) small unit ( SI unit ) watt hour (wh) bigger unit
kilowatt hour (kWh)even bigger
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