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Name the scientist who discovered
X-rays
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Name the scientist who discovered Visible light
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Name the scientist who discovered Microwaves
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Name the scientist who discovered radio waves
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Name the scientist who discovered Infra-red waves
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Name the scientist who discovered Ultraviolet rays
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Two waves A and B have wavelength 0.01 Å and 9000 Å respectively.
Name the two waves. compare the speeds of these waves when they travel in vacuum.
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| Gamma rays | D | C | Visible light | B | A |
The above table shows different parts of the electromagnetic spectrum.
(a) Identify the parts of the spectrum marked as A, B, C and D.
(b) Which of the radiations A or B has the higher frequency?
(c) State two properties which are common to all parts of the electromagnetic spectrum.
(d) Name one source of each of the radiation of electromagnetic spectrum.
(e) Name one detector for each of the radiation.
(f) Name one use of each of the radiation.
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- Calculate the speed of the wave.
- Name the medium through which it is traveling.
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In equilibrium algebraic sum of moments of all forces about the point of rotation is ______.
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The moon revolving around the earth is in ______ equilibrium.
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In figure, a uniform bar of length l m is supported at its ends and loaded by a weight W kgf at its middle. In equilibrium, find the reactions R1 and R2 at the ends.
`["Hint:" "In equilibrium" "R"_1 + "R"_2 = "W" "and" "R"_1 xx l/2 = "R"_2 xx l/2]`
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State the condition when the work done by a force is negative. Explain with the help of examples.
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A man spends 7.4 kJ energy in displacing a body by 74 m in the direction in which he applies force, in 2.5 s. Calculate the power spent (in H.P) by the man.
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A pump is used to lift 600 kg of water from a depth of 75 m in 10s. Calculate:
- The work done by the pump,
- the power at which the pump works, and
- The power rating of the pump if its efficiency is 40%. (Take g = 10m s-2).
`["Hint" : "Efficiency" = "useful power"/"power input"]`
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