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In the following figure, show two rays A and B travelling from water to air. If the critical angle for water- air surface is 48°, complete the ray diagram showing the refracted rays for each. State conditions when the ray will suffer total internal reflection.
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A lens forms the image of an object placed at a distance 15 cm from it, at a distance 60 cm in front of it. Find the focal length.
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A convex lens forms an inverted image of size same as that of the object which is placed at a distance 60 cm in front of the lens. Find:
- The position of the image, and
- The focal length of the lens.
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A concave lens forms an erect image of `1/3`rd the size of the object which is placed at a distance 30 cm in front of the lens. Find:
- the position of image, and
- the focal length of the lens.
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The focal length of a convex lens is 25 cm. Express its power with sign.
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The power of a lens is -2.0 D. Find its focal length and its kind.
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Describe how you would determine the focal length of a converging lens, using a plane mirror and one pin. Draw a ray diagram to illustrate your answer.
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The bells of a temple are big in size. Why?
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Two resistors of resistance 4 Ω and 6 Ω are connected in parallel to a cell to draw 0.5 A current from the cell.
Draw a labeled diagram of the arrangement
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Two resistors of resistance 4 Ω and 6 Ω are connected in parallel to a cell to draw 0.5 A current from the cell.
Calculate current in each resistor.
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A particular resistance wire has a resistance of 3 ohm per meter. Find the potential difference of the battery which gives a current of 2 A in each of the 1.5 m length when connected in the parallel to the battery (assume that resistance of the battery is negligible).
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A particular resistance wire has a resistance of 3 ohm per meter. Find :
The total resistance of three lengths of this wire each 1.5 m long, in parallel.
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An electrical appliance has a rating 100 W, 120V. The resistance of element of appliance when in use:
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A current of 2 A is passed through a coil of resistance 75 Ω for 2 minutes.
(a) How much heat energy is produced?
(b) How much charge is passed through the resistance?
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An electrical appliance having a resistance of 200 Ω is operated at 200 V. Calculate the energy consumed by the appliance in 5 minutes in kWh.
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An a.c. generator changes the ______energy to ______ energy.
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State two safety measures to be taken while establishing a nuclear power plant.
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What is meant by nuclear waste?
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Name the principle on the basis of which optical fibres work.
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How does a ray of light bend when it travels from rarer to denser medium
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