Question

Gravitational forces exerted by the Sun and the Moon are mainly responsible for ocean tides. Which of the following statement(s) regarding ocean tides is/are correct?

• A. Tidal amplitude corresponding to diurnal period is larger than that of the semi-diurnal period.
• B. Diurnal time period of lunar forced tides is longer than that of the solar forced tides.
• C. Tidal amplitudes are larger during a solar eclipse compared to that during a lunar eclipse.
• D. Tides are absent during equinoxes.

Hint:

During a solar eclipse, the Sun and Moon's gravitational forces combine, leading to higher tidal amplitudes, known as spring tides.

Answer 1

The Correct Option is B, C

Tides are primarily caused by the gravitational interactions between the Earth, the Moon, and the Sun. These interactions create periodic variations in the ocean's surface, known as tidal oscillations. Let's analyze each option carefully:
(A) Tidal amplitude corresponding to diurnal period is larger than that of the semi-diurnal period.
This statement is generally false. Semi-diurnal tides (which have two high tides and two low tides per day) are more common and have larger amplitudes compared to diurnal tides (which have only one high tide and one low tide per day) in most parts of the world. The tidal amplitudes depend on the specific location and the alignment of the Sun and Moon, but typically, semi-diurnal tides have higher amplitudes. (B) Diurnal time period of lunar forced tides is longer than that of the solar forced tides.
This statement is true. The lunar tidal cycle (diurnal tide) is approximately 24 hours and 50 minutes. In comparison, the solar tidal cycle (which has a slightly longer period due to the Earth's orbit) is approximately 24 hours. The moon's gravitational pull causes the diurnal lunar tides to be slightly longer than the solar tides, resulting in a longer lunar tidal period. (C) Tidal amplitudes are larger during a solar eclipse compared to that during a lunar eclipse.
This statement is true. During a solar eclipse, the Sun and the Moon are aligned on the same side of the Earth, and their gravitational forces combine to create higher tidal amplitudes (known as spring tides). In contrast, during a lunar eclipse, the Sun, Earth, and Moon are aligned, but the gravitational forces do not combine as effectively, resulting in lower tidal amplitudes. (D) Tides are absent during equinoxes.
This statement is false. Tides do not disappear during equinoxes. In fact, during equinoxes, the Earth experiences spring tides (higher tides), as the gravitational forces of the Sun and Moon align more effectively, producing higher tidal amplitudes. Equinoxes refer to the time of year when the day and night are of equal length, but this does not affect the occurrence of tides. Thus, the correct answers are (B) and (C).