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प्रश्न
Complete the analogy.
Height of a person: cm :: Length of your sharpened pencil lead:______?
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उत्तर
Height of a person: cm :: Length of your sharpened pencil lead: mm (millimetre).
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संबंधित प्रश्न
The principle of ‘parallax’ in section 2.3.1 is used in the determination of distances of very distant stars. The baseline AB is the line joining the Earth’s two locations six months apart in its orbit around the Sun. That is, the baseline is about the diameter of the Earth’s orbit ≈ 3 × 1011m. However, even the nearest stars are so distant that with such a long baseline, they show parallax only of the order of 1” (second) of arc or so. A parsec is a convenient unit of length on the astronomical scale. It is the distance of an object that will show a parallax of 1” (second) of arc from opposite ends of a baseline equal to the distance from the Earth to the Sun. How much is a parsec in terms of meters?
Exercise
While measuring the length of an object using a ruler, the position of your eye should be
A hand span is a reliable measure of length.
Metre is the unit of ______.
Which line is longer? C or D? Measure each line. How good is your guess?
What is the length of a 100 rupee note? Guess. Now measure it using a scale.
Yard was used as the unit of length.
- The earth-moon distance is about 60 earth radius. What will be the diameter of the earth (approximately in degrees) as seen from the moon?
- Moon is seen to be of (½)°diameter from the earth. What must be the relative size compared to the earth?
- From parallax measurement, the sun is found to be at a distance of about 400 times the earth-moon distance. Estimate the ratio of sun-earth diameters.
If a planet subtends an angle α at distance D, what formula is used to find the planet's diameter?
