Which one of the following radiations has longer wavelength?
- A.X-rays
- B.Ultraviolet
- C.Micro Wave
- D.Infra-red
Correct answer
Explanation
The correct answer is C, Micro Wave. Among the four, microwaves lie farthest towards the long-wavelength end of the electromagnetic spectrum.
In order of increasing wavelength the spectrum runs: gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves and radio waves. Microwaves have wavelengths from about a millimetre to about 30 centimetres, while infrared waves are shorter than a millimetre. Because energy falls as wavelength rises, microwaves also carry less energy per photon than the other three options. They are used in radar, satellite links and microwave ovens, where they make water molecules in food vibrate.
A, X-rays, have wavelengths of around a nanometre or less, far shorter than microwaves.
B, ultraviolet, lies just beyond violet light, with wavelengths of roughly 10 to 400 nanometres.
D, infra-red, is longer than visible light but still shorter than microwaves.
Exam tip: remember the order Gamma, X, UV, Visible, IR, Micro, Radio; wavelength rises and energy falls along it.
Practice Questions
View allWhich one of the following cell organelles contains DNA?
- A.Golgi apparatus
- B.Mitochondrion
- C.Lysosome
- D.Endoplasmic reticulum
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Mitochondria carry their own small, circular DNA and their own ribosomes. Mitochondria are the powerhouses of the cell, where aerobic respiration makes ATP.
Read the full explanation →Which set of vegetables is underground stem or modified stem of a plant?
- A.Potato, artichoke, round gourd
- B.Onion, garlic, carrot
- C.Potato, onion, garlic
- D.Potato, garlic, turnip
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All three are underground modified stems: the potato is a stem tuber, and onion and garlic are bulbs. A stem can be told from a root by its nodes and buds.
Read the full explanation →A sound wave having frequency of 300 Hz is travelling in an unknown medium. Its wavelength is not known. It travels a distance equal to 150 times its wavelength in time t. The value of t is :
- A.0.5 s
- B.1 s
- C.1.5 s
- D.2 s
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A wave moves forward by one wavelength in each cycle, so 150 wavelengths take 150 cycles, and 150 cycles at 300 per second take half a second.
Read the full explanation →A body floats in a liquid if the buoyant force is :
- A.equal to its weight.
- B.less than its weight.
- C.greater than its weight.
- D.zero.
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A floating body is in equilibrium, so the upward buoyant force exactly balances its weight. By Archimedes' principle, a body in a liquid is pushed up by a force equal to the weight of the liquid it displaces.
Read the full explanation →Which of the following are the different parts of a human brain ?
- A.Forefront brain, Standard brain and Hind brain
- B.Fore brain, Median brain and Rear brain
- C.Fore brain, Mid brain and Hind brain
- D.Precursor brain, Mean brain and Hind brain
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These are the three main divisions of the human brain. The fore brain is the largest part.
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