CLASS-VII
SUBJECT-GEOGRAPHY
CHAPTER 5 : WATER
1. Define – Tsunami. How is it caused?
Ans. –
- A huge tidal wave is called tsunami. An earthquake, a volcanic eruption or underwater landslides can shift large amounts of ocean water. As a result a huge tidal wave called tsunami is formed.
- As a result a huge tidal wave called tsunami is formed.
2. What are waves? How are they caused?
Ans. –
- When the water on the surface of the ocean rises and falls alternately, they are called waves.
- Waves are formed when winds scrape across the ocean surface.
- The stronger the wind blows, the bigger the wave becomes.
3. What are tides?
Ans. – The rhythmic rise and fall of ocean water twice in a day is called a tide.
4. What are the causes of tides? Explain neap tides and spring tides.
- The strong gravitational pull exerted by the sun and the moon on the earth’s surface causes the tides.
- The water of the earth closer to the moon gets pulled under the influence of the moon’s gravitational force and causes high tide.
- During the full moon and new moon days, the sun, the moon and the earth are in the same line and the tides are highest. These tides are called spring tides.
- When the moon is in its first and last quarter, the ocean waters get drawn in diagonally opposite directions by the gravitational pull of sun and earth resulting in low tides. These tides are called neap tides.
5. What are ocean currents?
Ans. –Ocean currents are streams of water flowing constantly on the ocean surface in definite directions.
6. Name the two types of ocean currents. What are its effects?
- The two types of ocean currents are warm and cold currents.
- The areas where the warm and cold currents meet provide the best fishing grounds of the world.
- Seas around Japan and the eastern coast of North America are such examples.
- The areas where a warm and cold current meet also experience foggy weather making it difficult for navigation.
7. List any three importance of tides.
Ans. – The three importance of tides are as follows-
- It helps in navigation.
- It helps in fishing.
- It is used to generate electricity.