The distance between two successive crests or troughs of sea waves is called as
- A.Wavelength
- B.Wave height
- C.Wave frequency
- D.Fetch
Correct answer
Explanation
The correct answer is A, Wavelength. The horizontal distance from one crest to the next, or from one trough to the next, is the wavelength.
Ocean waves are mostly made by wind blowing over the sea surface. The highest point of a wave is its crest and the lowest point is its trough. Water particles in a wave move in roughly circular paths, so the wave form travels forward while the water itself mostly stays in place. Geographers describe a wave by a few measures: wavelength, wave height, wave period (the time between two crests passing a point) and wave frequency. When waves reach shallow water near the coast, they slow down, grow taller and finally break as surf.
B is wrong: wave height is the vertical distance from the trough to the crest.
C is wrong: wave frequency is the number of waves passing a fixed point in one second.
D is wrong: fetch is the stretch of open water over which the wind blows; a longer fetch builds bigger waves.
Exam tip: Crest to crest = wavelength; trough to crest = wave height; waves per second = frequency; wind's run over water = fetch.
Practice Questions
View allD performs her train journey by the shortest route from Bengaluru to New Delhi. Which one of the following rivers will she not cross while performing the journey?
- A.Narmada
- B.Yamuna
- C.Godavari
- D.Krishna
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The shortest rail route from Bengaluru reaches Delhi from the south through Agra and Mathura, which lie on the western side of the Yamuna, so the train never has to cross that river.
Read the full explanation →In India, the period of steady population growth refers to the decade(s) of:
- A.1981-2011
- B.1951-1981
- C.1921-1951
- D.1911-1921
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In the standard division of India's population history, the three decades from 1921 to 1951 are called the period of steady population growth.
Read the full explanation →Consider the following statements with reference to earthquakes:
1. Collapse earthquakes are most common.
2. Tsunamis are waves generated by the tremors and not an earthquake in itself.
3. High magnitude earthquakes i.e. 8+ are quite rare whereas 'tiny' types occur almost every minute.
Which of the statements given above are correct?
- A.1 and 2 only
- B.1 and 3 only
- C.2 and 3 only
- D.1, 2 and 3
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Statement 1 is false because tectonic earthquakes, not collapse earthquakes, are the most common type. Earthquakes are grouped by cause: tectonic (sliding of rocks along a fault), volcanic, collapse (the roofs of underground mines or caverns falling in), explosion (from nuclear or chemical blasts) and reservoir-induced.
Read the full explanation →With reference to earthquakes, which of the following statements are correct?
1. Earthquakes largely occur along the converging plate boundaries.
2. Point of origin of earthquake in lithosphere is known as focus/hypocentre.
3. Intensity of earthquake decreases with distance from the epicentre.
4. Epicentre of earthquake always remains over continents only.
Select the correct answer using the code given below.
- A.1 and 2 only
- B.1, 2 and 3
- C.2 and 3 only
- D.1 and 4
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The first three statements are true, while statement 4 is false because many earthquakes have their epicentre under the sea.
Read the full explanation →National Disaster Management Authority is headed by
- A.the Prime Minister.
- B.the Home Minister.
- C.the President.
- D.the Health Minister.
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Under the Disaster Management Act, 2005, the Prime Minister is the ex officio chairperson of the National Disaster Management Authority (NDMA).
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