Questions Answers For All Chapters – Geography Class 8
Ocean Currents
Q 1. Choose the correct option :
(a) In which ocean does the Labrador current flow?
(i) Pacific
(ii) South Atlantic
(iii) North Atlantic
(iv) Indian
Answer: (iii) North Atlantic
(b) Which current out of the following flows in the Indian Ocean?
(i) East Australian Current
(ii) Peru current
(iii) South Polar current
(iv) Somali current
Answer: (iv) Somali current
(c) Which factor out of the following does not affect the region along the coast?
(i) Precipitation
(ii) Temperature
(iii) Land breezes
(iv) Salinity
Answer: (iv) Salinity
(d) Which of the following occurs in the area where the cold and warm currents meet?
(i) High temperature
(ii) Snow
(iii) Low temperature
(iv) Thick fog
Answer: (iv) Thick fog
(e) Which of these following currents flows from the northern polar region upto Antarctica?
(i) Warm ocean currents
(ii) Surface ocean currents
(iii) Cold ocean currents
(iv) Deep ocean currents
Answer: (iii) Cold ocean currents
Q 2. Examine the given statements and correct the wrong ones.
(a) Ocean currents give specific direction and velocity to the water
Answer: Correct – Ocean currents give specific direction and velocity to the water.
(b) The deep ocean currents flow with high velocity
Answer: Wrong – Deep ocean currents flow with low velocity, not high velocity.
(c) Generally, surface ocean currents are formed in the equatorial regions.
Answer: Correct – Generally, surface ocean currents are formed in the equatorial regions.
(d) Ocean currents hold great importance for human life.
Answer: Correct – Ocean currents hold great importance for human life.
(e) The movement of icebergs is not dangerous for water transport.
Answer: Wrong -The movement of icebergs is dangerous for water transport, as they can obstruct the routes of ships.
(f) Water becomes warm near Brazil due to ocean currents. On the other hand, it becomes cold near African coast.
Answer: Correct -Water becomes warm near Brazil due to ocean currents. On the other hand, it becomes cold near the African coast.
Q 3. Explain the effect of –
(a) Warm ocean currents on climate
Answer: Warm ocean currents increase the temperature of coastal areas, making the climate warmer. They also increase precipitation by increasing moisture in the air.
(b) Cold ocean currents on the movement of icebergs
Answer: Cold ocean currents carry icebergs from polar regions into warmer waters, making them dangerous for ships.
(c) The shape of the coast line on ocean currents
Answer: The alignment of the coastline influences the direction of ocean currents. Currents change their direction according to the shape of the land.
(d) Meeting of warm and cold ocean currents
Answer: When warm and cold currents meet, thick fog is formed, and it creates rich fishing grounds due to the availability of plankton.
(e) The transportational capacity of ocean currents
Answer: Ocean currents increase the speed of ships and reduce fuel consumption when ships follow the direction of the currents.
(f) Deep ocean currents
Answer: Deep ocean currents are caused by differences in temperature and salinity. Cold, dense water sinks and moves to different parts of the ocean, circulating nutrients.
Q 4. Look at the map of ocean currents and answer the following :
(a) How does the Humboldt current affect the climate of the South American coast?
Answer: The Humboldt Current lowers the temperature along the South American coast and creates dry, desert-like conditions.
(b) In which oceans are counter equatorial currents not observed and why?
Answer: Counter equatorial currents are not observed in the Indian Ocean because of the seasonal reversal of Monsoon winds.
(c) Which currents are absent in northern part of the Indian Ocean and why?
Answer: Cold currents are absent in the northern part of the Indian Ocean because it is landlocked to the north, limiting the flow of cold currents.
(d) In which regions do the cold and warm ocean currents meet?
Answer: Cold and warm ocean currents meet near Newfoundland (Gulf Stream and Labrador Current) and near the coast of Japan (Kuroshio and Oyashio Currents).
Q 5. Answer the following questions:
(a) What are the reasons responsible for the formation of deep ocean currents?
Answer: Deep ocean currents are caused by differences in temperature and salinity (thermohaline circulation). Cold, salty water is denser and sinks, creating deep currents.
(b) What is the reason behind the dynamics of the ocean water?
Answer: Differences in temperature, salinity, and planetary winds drive the movement of ocean water.
(c) How do winds give direction to the ocean currents?
Answer: Planetary winds push ocean currents, causing them to move in a circular pattern—clockwise in the Northern Hemisphere and anti-clockwise in the Southern Hemisphere.
(d) Why do the ports in the eastern coast of Canada freeze in winter?
Answer: Ports in eastern Canada freeze because the Labrador Current brings cold water and icebergs from the Arctic, lowering the temperature of the coastal waters.
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