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Q9. Hot water is a commodity in developing communities. Firewood is increasingly

ID: 1661688 • Letter: Q

Question

Q9. Hot water is a commodity in developing communities. Firewood is increasingly scarce, is expensive, and has drawbacks. A curved mirror can be used to boil water without electricity or gas, just using energy from the sun, and thus can be a cheaper and more environmentally friendly solution allowing more people in developing communities to have access to hot water ! 1) Why is a concave mirror used (not a convex or plane mirror)? 2) Where would you place the container of water you wish to heat using solar power? 3) A curved spherical mirror has a cross-sectional area of 0.5 m2. Sunlight hits the mirror with an intensity [Power/area] of 970 Watts/m2. What is the power in Watts at the focal point assuming all the light is reflected? (How does this compare to a typical light bulb?)

Explanation / Answer

1)concave mirror is used because it is converging mirror.If light coming parrallely ,they all will converge at the focal length of mirror

2)object must be kept at focal length og mirror

3)power=intensity*area=485 W

A light bulb has power almost same as this one