1. R = +32 cm f=R/2 =+32/2=+16cm The focal length of the given convex mirror is 16 cm.

    R = +32 cm
    f=R/2
    =+32/2=+16cm
    The focal length of the given convex mirror is 16 cm.

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  2. (i) Wind mill farms are constructed to produce electricity. (ii) The traditional use of energy of flowing water has been modified by establishing hydro-power plants. At hydro-power plants, the energy of falling water or flowing water is tapped by using a water turbine and then made to drive generatoRead more

    (i) Wind mill farms are constructed to produce electricity.
    (ii) The traditional use of energy of flowing water has been modified by establishing hydro-power plants. At hydro-power plants, the energy of falling water or flowing water is tapped by using a water turbine and then made to drive generators.

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  3. We are looking at alternate sources of energy because the fossil fuels and nuclear fuels on the earth are limited which may not last for long and the undesirable effects of pollution, both from the burning of fossil fuels and from the radioactive nuclear wastes of nuclear power plants are creating tRead more

    We are looking at alternate sources of energy because the fossil fuels and nuclear fuels on the earth are limited which may not last for long and the undesirable effects of pollution, both from the burning of fossil fuels and from the radioactive nuclear wastes of nuclear power plants are creating threat to our environment.

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  4. Disadvantages of fossil fuels are: (i) The burning of fossil fuels produces large amount of carbon dioxide that causes increased greenhouse effect. (ii) The burning of fossil fuels (such as coal) produces smoke which pollutes the air. (iii) The burning of fossil fuels produces acidic gases such as sRead more

    Disadvantages of fossil fuels are:
    (i) The burning of fossil fuels produces large amount of carbon dioxide that causes increased greenhouse effect.
    (ii) The burning of fossil fuels (such as coal) produces smoke which pollutes the air.
    (iii) The burning of fossil fuels produces acidic gases such as sulphur dioxide and nitrogen oxide. These acidic gases cause acid rain that affects our water and soil resources.
    (iv) Fossil fuels cannot be replenished in short time because it takes millions of years to form them.

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  5. (i) They cause air, water and soil pollution. (ii) They may cause bio-magnification in the food chain and end up in humans.

    (i) They cause air, water and soil pollution.
    (ii) They may cause bio-magnification in the food chain and end up in humans.

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