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igcse physics notesprinted 54 Β· PDF 54
124 pagesrevision 46936
printed 54 Β· PDF 54
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54
P=1.9 x 106J/s
(ii) (You will study this in greater detail later).
For now use the formula Electrical Power=VI
Where V=Voltage and I=Current
Explanation:
Efficiency=
ππ πππ’π πππ€ππ ππ’π‘ππ’π‘
πππ‘ππ πππ€ππ ππππ’π‘π₯ 100%
Total Power input= Power given to Power Scheme= Rate of GPE transfer
Useful Power output= Power produced by power scheme
Useful power output= VI = 6000 x 270 =1.62 x 106J/s
Total power input= 1.93x 106J/s
Efficiency (1.62 x 106/1.93 x 106) x 100%
Efficiency=83.91β¦ β84%(This answer is slightly different from the marking
scheme because they have used the value of g as 10.
(c)(i) Damage to fish habitats/ Risk of flooding/ Loss of land
(ii) (Write any one). Solar/Wind/Geothermal/Tidal/Waves/Biofuel
4)
(a) The principle of conservation of energy states that energy cannot be
created or destroyed, rather it can only be changed from one form to another.
(b)(i) (You will also learn more about this in electrical power). One kWh is the
amount of energy transferred in one hour at the rate of transfer of 1kW (which
equals 3.6 x 106J).
(b)(ii) Use the definition above to help you.
P=E/t
E= P x t, E= 1.8 x 106 x 4 x 3600
E=2.592x 1010J
1kWh= 3.6 x 106 J
2.592 x 1010/ 3.6 x 106= 7200 kWh