Explore topic-wise InterviewSolutions in .

i. crest

ii. trough

iii. amplitude

iv. wave length

v. tsunamis

The sea water gets pushed by the wind and so ripples are generated on the water surface. These are called waves.

(i) The sea water gets pushed up & down because of the wind. The raised up portion of the wave is called crest & the depressed one is called trough.

(ii) The vertical distance between a crest and the following trough is called the amplitude of the wave whereas the distance between two successive crests or troughs is called wave length.

(iii) The wave length, its amplitude & its velocity depend on the velocity of the wind.

By blowing air with your mouth on the water surface of the dish.

• By dropping an object in the dish.
• By blowing air on the water surface.
• By strong fan breeze.

Due to the earth’s rotation, the earth gets a type of power or force. This force works away from the centre. It is called the centrifugal force.

The positive effects of tides are as follows:

• The tides clear the waste and hence the coasts become clean.
• Ports do not get filled with sediments.
• Ships can move up to the ports during high tide.
• During high tide, sea water can be stored in salt pans from which salt can be obtained.
• The tidal force can be used to generate electricity.
• With the high tide, fish move into the creeks and this helps fishing activity.
• The tides help in maintaining the mangroves and the coastal biodiversity.

The negative effects of tides are as follows:

• A lack of an understanding of the timings of high and low tides may cause accidents to swimmers entering the sea.

The alternate rising and falling of the sea water after a specific period is called tide.

(i) While revolving around the earth, the moon makes a right angle with respect to the earth and the sun, twice a month.

(ii) This position occurs on the first and third quarter of each month. On both these days the forces of both the sun & the moon operate at right angles on the earth.

(iii) At the places where the sun causes high tide, the gravitational pull of the moon which is at right angles also acts on the water.

(iv) Due to such conditions the water level rise is less than usual at the time of high tide. Similarly, fall in water level is less than usual at the time of low tide.

(v) Such tides are called neap tides.

• While revolving around the earth, the moon makes a right angle with respect to the earth and the sun.
• This position occurs on the first and the third quarter of each month.
• On both these days, the forces of both the sun and the moon operate at right angles on the earth.
• The attraction of the sun and the moon are not complementary but at right angles to each other.
• Due to this, the water level rise is less than usual at the time of high tide.

i. Natural

ii. Tides

iii. Gravitational

iv. Low

v. Minimum

(i) Generally the areas along the sea coast are low lying and get flooded easily by the sea water during high tide.

(ii) This leads to accumulation of sea water over a long period of time leading to formation of swamps & marshes.

(iii) The tides help in maintaining the mangroves and the coastal biodiversity here.

(iv) Certain areas near the sea coast being low lying & waters being shallow also lead to sediment deposition by sea waves leading to formation of lagoons.

(v) In this way, at some places along the coast, the low lying areas turn into lagoons or marshy lands.

With the high tide, fish moves into the creeks and this helps the fishing activity.

Ships can move up to the ports during high tide.

A lack of an understanding of the timings of high and low tides may cause accidents to swimmers entering the sea.

Plan for going to trips after full moon or new moon day. Also one must have details about the timings of the tides for better enjoyment.

The wave length is the distance between two successive crests or troughs.