CAPF AC 2025 Q77: Geography – Oceanography
- (a) 1 only
- (b) 2 only
- (c) 1 and 2
- (d) 2 and 3
Answer: (d) 2 and 3
Explanation
Neap tides
How to think: neap tides come at the quarter moons, when the Sun and Moon pull at right angles and cancel part of each other's effect.
| Statement | Fact | Verdict |
|---|---|---|
| 1. A seven-day interval between two neap tides | Neaps are about 14 days apart; the 7-day gap is between a spring tide and the next neap | Wrong |
| 2. The Sun and Moon are at right angles | At first and last quarter, the Sun, Earth and Moon form a right angle | Correct |
| 3. The Moon's pull is lessened by the Sun's counteracting pull | The Sun's gravity works against the Moon's pull, giving a low tidal range | Correct |
Statements 2 and 3 are correct.
Bank key corrected: the stored key was (c) 1 and 2; the right answer is (d) 2 and 3.
Answer: (d) 2 and 3.
Why each option is right or wrong
- (a) Incorrect. Statement 1 mixes up the interval between neap tides with that between spring and neap.
- (b) Incorrect. Statement 3 is also correct.
- (c) Incorrect. Statement 1 is wrong, and statement 3 is left out.
- (d) CORRECT. Statements 2 and 3 describe neap tides.
Key point
Spring tide: new and full moon, Sun, Moon, Earth in a line, highest range. Neap tide: first and last quarter, right angle, lowest range. Interval of about 7 days between a spring and the following neap; two neaps are about 14 days apart.
Remember
Neap: quarter moon, right angle, pulls cancel; neaps are 14 days apart.
Common mistakes
- Taking the 7-day gap between spring and neap as the gap between two neaps.
- Believing neap tides happen at full moon.
- Thinking the Sun adds to the Moon's pull at neap tide; it opposes it.
Exam tip
Educated guess: two spring tides come every fortnight and so do two neaps. A seven-day gap between neaps would mean one every week, which is too frequent.
Sources
- NCERT Class XI Fundamentals of Physical Geography, chapter on Movements of Ocean Water: tides, spring tides and neap tides
- National Oceanic and Atmospheric Administration (NOAA), What are spring tides and neap tides?