The neap tide definition is which of the following?

• A. Largest range, full/new moon
• B. Largest range, full moon
• C. Smallest range, quarter moon
• D. No tide

Answer: (C)

Tides vary with the Moon’s phase because the Sun and Moon's gravity combine differently as the Moon orbits. At the first and last quarter phases, the Sun and Moon pull in roughly perpendicular directions relative to Earth, so their tidal effects partially cancel each other. This leads to a smaller difference between high and low tides—the smallest tidal range. That’s why the description of the neap tide is a small tidal range at quarter moon.

In contrast, when the Moon is new or full, the Sun and Moon align with Earth and their gravitational pulls reinforce each other, producing a larger tidal range (spring tides). The idea of “no tide” isn’t accurate because gravitational forces from both the Sun and Moon always create some tidal movement.