Ocean water movement - class-VIII

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Neap tides, i.e., small tides are caused when _____________________.

  1. Sun, and moon are at right angles

  2. Sun, earth and moon are in one line

  3. There is new moon

  4. There is full moon

Correct Option: A

The rise and fall of the sea-water at the surface at constant intervals is known as __________.

  1. Bore

  2. Tides

  3. Waves

  4. Water drift

Correct Option: B

Which of the following statements is not correct about the ocean currents?

  1. Currents do not exert an influence on the climatic conditions of the coasts

  2. Winds play an important role in the circulation of the ocean currents

  3. Currents are produced by the differences in the density of the sea water at different depths

  4. Direction of ocean currents is influenced by the shape and position of coasts

Correct Option: A

Which of the following is not an effect of the ocean currents?

  1. They effect commerce because they keep the harbours open even during winter

  2. Water of the ocean is kept pure

  3. Warm equatorial currents lower the temperature of the places through which they pass

  4. They do not effect rainfall over the coasts

Correct Option: D

Spring tides are caused, when _____________________.

  1. The earth, moon and sun are in a line

  2. The moon and sun are on a line

  3. The sun and moon are at right angles to each other and the earth is at the centre

  4. There is new moon

Correct Option: A

Neap tides occur _______________.

  1. On new and full moon days

  2. On first and third quarters of the month

  3. Twice daily

  4. On every full moon

Correct Option: B

The tides in the seas are influenced both by the sun and the moon. This fact is proved by ________________.

  1. The spring and the neap tides

  2. The bores

  3. Ebb tides

  4. Oceanic currents

Correct Option: A

Tides are caused because of ___________________.

  1. Gravitational pull of the sun

  2. Gravitational pull of the moon

  3. Gravitational pull of the earth towards its axis

  4. Difference in the temperatures of water of the sea at different depths

Correct Option: B

The part of the sea which touches the land and is generally not so deep is called ______________.

  1. The high sea

  2. The continental shelf

  3. Isthmus

  4. Lake

Correct Option: B

Which of the following is a type of wave ____________.

  1. Ripples

  2. Seas

  3. Swells

  4. All are the types of waves

Correct Option: D

Ripples are the instant effect of wind on water and they die down as quickly as they form, as the surface tension of the water dampens their efforts.

Waves always travel in the same direction as the wind is blowing: if the wind changes then the waves change with it. Wave size is determined by the strength of the wind, the length of time it has been blowing and the distance it has blown over or the ‘fetch’.

When strong winds blow for longer than a few hours, it gives the water sufficient energy that it then takes on a character of its own. This character and movement is known as swell, and it will march across open areas of water independent of the wind.

Which is the busiest of Ocean trade routes ?

  1. North Pacific Ocean

  2. Indian Ocean

  3. Arctic Ocean

  4. North - Atlantic Ocean

Correct Option: D
Atlantic Ocean
The busiest ocean from the point of view of trade is Atlantic Ocean.

Large movements of ocean water from places of warm temperature to low temperature or vice versa are ______________.

  1. Drifts

  2. Ocean currents

  3. Waves

  4. Tides

Correct Option: B

Kuroshio current is available in ___________.

  1. North Pacific Ocean

  2. North Atlantic Ocean

  3. North Indian Ocean

  4. None of these

Correct Option: A

The north equatorial current turns northward to the obstruction of Philippines and thus gives birth to the Kuroshio current which flows from Taiwan to Ryuku ridge at 30 degrees N latitude. The Kuroshio current is a warm current. The average temperature and salinity are 8 degrees and 35% respectively.

Which factors influence ocean currents?

  1. Earth's rotation

  2. Winds across ocean

  3. Density of water

  4. All of the above

Correct Option: D

Factors Influencing Nature and Movement of Ocean Currents:

1. Factors related to the earth’s rotation: Gravitational force and force of deflection.

2. Factors originating within the sea: Atmospheric pressure, winds, precipitation, evaporation and insolation.

3. Factors originating within the sea: Pressure gradient, temperature difference, salinity, density and melting of ice.

4. Factors modifying the ocean currents: Direction and shape of the coast, seasonal variations and bottom topography.

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