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9 Cards in this Set
- Front
- Back
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A Child's toy is operated b a small motor. The potential difference across the motor is 6.0 V and the current in it is 0.20 A. The energy used by the motor in 120s is A 2.40 J B 60.0 J C 144 J D 3600 J |
0.2 x 6 x 120 C 144 J |
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The heating element for an electric fire is made from a wire of resistance R. It is replaced with a wire of the same material which has the same length but is twice the diameter. The resistance of the second wire is A 1/4R B 1/2R C 2R D 4R |
A 1/4R |
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Explain, in terms of energy, the difference between potential difference (p.d.) and electromotive force (emf). [2 marks] |
p.d. is electrical energy(/coulomb) transferred between twopoints/electrical energy transformed/converted to other forms (1) e.m.f is the energy(/coulomb) supplied to a circuit/given to thecharge/energy output of the cell (1) |
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![Two lamps A and B are connected in parallel. State which bulb will be brighter and explain your answer.
[3 marks]](https://images.cram.com/images/upload-flashcards/42/46/42/17424642_m.png)
Two lamps A and B are connected in parallel. State which bulb will be brighter and explain your answer. [3 marks] |
Resistors in parallel have same p.d (1) Identifies P = V2 /R OR P =VI and IA > IB (1) Uses this equation to state PA.> P B .OR bulb A brighter than bulb B. Consequent on 2nd marking point (1) |
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Increasingly a different type of light bulb is being used. It is a coiled fluorescentbulb. A 10 W bulb of this type could replace the 60 W filament bulb and give thesame visible light intensity on the floor. Approximately 25% of national power production is used for lighting. Discuss why some countries have announced that filament bulbs will be banned inthe next few years. [3 marks] |
Any three: Fluorescent lamp much more efficient OR filament lamp is lessefficient(1) Sensible attempt to process the values given (1)Indicates that less than 25% of national power used for lighting (1) Reduction in wasted energy as thermal energy (1) Reduction in CO2 emission or preserves fossil fuel resources (1) |
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The diagram shows a resistor network. The total resistance between x and y is A 0.25Ω B 1.0Ω C 4.0Ω D 16Ω |
C 4.0Ω |
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A volt can be defined as A a coulomb per joule B a coulomb per second C a joule per coulomb D a joule per second |
C a joule per coulomb |
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Two identical resistors connected in series have a total resistance of 8Ω. The same two resistors when connected in parallel have a total resistance of A 0.5Ω B 2Ω C 4Ω D 8Ω |
B 2Ω |
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A |
