NCERT Solutions For Class 11 Geography Chapter 13 Movements of Ocean Water - 2025-26

1. Multiple choice questions.

i. Upward and downward movement of ocean water is known as the :

• (a) tide
• (b) current
• (c) wave
• (d) none of the above

Answer: (a) tide.

ii. Spring tides are caused :

• (a) As result of the moon and the sun pulling the earth gravitationally in the same direction.
• (b) As result of the moon and the sun pulling the earth gravitationally in the opposite direction.
• (c) Indention in the coast line.
• (d) None of the above.

Answer: (a) As result of the moon and the sun pulling the earth gravitationally in the same direction.

iii. The distance between the earth and the moon is minimum when the moon is in :

• (a) Aphelion
• (b) Perigee
• (c) Perihelion
• (d) Apogee

Answer: (b) Perigee.

iv. The earth reaches its perihelion in:

• (a) October
• (b) September
• (c) July
• (d) January

Answer: (d) January.

2. Answer the following questions in about 30 words.

i. What are waves?

Answer: Waves are the energy that moves across the ocean surface. They appear as the rise and fall of water, but the water particles themselves move in small circles as the wave passes, transferring energy rather than the actual water.

ii. Where do waves in the ocean get their energy from?

Answer: Waves in the ocean get their energy primarily from the wind. As wind blows over the water's surface, it transfers energy to the water, creating waves that travel across the ocean.

iii. What are tides?

Answer: Tides are the periodical rise and fall of sea level once or twice daily. They are mainly caused by the gravitational pull of the moon and, to a lesser extent, the sun on the earth’s oceans.

iv. How are tides caused?

Answer: Tides are caused by the gravitational attraction of the moon and the sun and the centrifugal force created by the rotation of the earth-moon system. This leads to the regular rise and fall of sea levels.

v. How are tides related to navigation?

Answer: Tides play an important role in navigation. Knowledge of tidal heights is crucial for ships entering and leaving harbours, especially those near river estuaries. High tides help ships to safely cross shallow bars.

3. Answer the following questions in about 150 words.

i. How do currents affect the temperature? How does it affect the temperature of coastal areas in the N. W. Europe?

Answer: Ocean currents, by moving large volumes of water, transport heat from one part of the world to another. Warm currents raise the temperature of coastal areas, while cold currents lower it.

For example, the North Atlantic Drift (a warm current) flows along the northwest coast of Europe. This warms the coastal regions of countries like the United Kingdom and Ireland, making their climates much milder than other places at similar latitudes.

As a result, these areas experience cool summers and mild winters, with a moderate temperature range. Conversely, cold currents lower the average temperature where they flow past a coast. Thus, ocean currents significantly influence the climate and temperature of coastal regions around the world.

ii. What are the causes of currents?

Answer: Ocean currents are caused by various factors. The primary causes include the heating by solar energy, which creates temperature differences and water expansion; wind, which imparts energy to the water’s surface; gravity, which pulls water down slopes created by temperature and salinity differences; and the coriolis force, which deflects the path of moving water due to Earth's rotation.

Secondary factors include variations in salinity and density, which cause vertical movement, and the shape of the ocean basins and coastlines, which determine the directions of the currents. Prevailing winds and the position of the continents also play significant roles in the formation and direction of ocean currents.

Understanding Movements of Ocean Water

The chapter on Movements of Ocean Water explores the fascinating phenomena of waves, tides, and ocean currents. Learning these fundamental processes helps students understand how the ocean shapes Earth’s climate and influences human activity across the globe.

Grasping the details of waves, tides, and currents will make concepts clearer and boost your exam preparation. Focus on differences between these movements and remember key examples like the North Atlantic Drift for thorough revision.

Regularly practicing NCERT-based questions will help reinforce your understanding. Revising these chapters will enhance conceptual clarity, helping you score better in Geography for the 2025-26 board exams and beyond.

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