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Unformatted text preview: .. ......................................................................... ......................................................................... ......................................................................... ......................................................................... 881-181 Turn over –8– N01/430/S(3) B3. When electrons are accelerated through a potential difference and strike a metal target, the following X-ray spectrum is produced. Relative Intensity Wavelength (a) Label the characteristic part of the spectrum. [1] (b) Explain the mechanism of how the characteristic part of the spectrum is produced. [3] ......................................................................... ......................................................................... ......................................................................... ......................................................................... ......................................................................... 881-181 –9– N01/430/S(3) Blank page 881-181 Turn over – 10 – N01/430/S(3) OPTION C — ENERGY EXTENSION C1. A wind generator converts wind energy into electric energy. The source of this wind energy can be traced back to solar energy arriving at the Earth’s surface. (a) Outline the energy transformations involved as solar energy converts into wind energy. [2] ......................................................................... ......................................................................... ......................................................................... ......................................................................... (b) List one advantage and one disadvantage of the use of wind generators. [2] Advantage: ......................................................................... ......................................................................... Disadvantage: ......................................................................... ......................................................................... The expression for the maximum theoretical power, P, available from a wind generator is P= where (c) 1 Aρ v 3 2 A is the area swept out by the blades, ! is the density of air and v is the wind speed. Calculate the maximum theoretical power, P, for a wind generator whose blades are 30 m long when a 20 m s −1 wind blows. The density of air is 1.3 kg m −3 . [2] ......................................................................... ......................................................................... ......................................................................... ......................................................................... (This question continues on the following page) 881-181 – 11 – N01/430/S(3) (Question C1 continued) (d) In practice, under these conditions, this generator only provides 3 MW of electrical power. (i) Calculate the efficiency of this generator. [2] ..................................................................... ..................................................................... ..................................................................... (ii) Give two reasons explaining why the actual power output is less than the maximum theoretical power output. [2] .....................................................................
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This note was uploaded on 09/30/2011 for the course CHEM 102 taught by Professor Tina during the Spring '11 term at Global.

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