At how many points along a complete sine wave is the voltage equal to zero?

In a complete sine wave, voltage crosses zero at specific points during its cycle. A standard sine wave oscillates smoothly between its maximum positive and maximum negative values, and the voltage is equal to zero when it transitions between these extremes.

Specifically, within one complete cycle of a sine wave, there are four key points where the voltage is zero as the wave transitions from positive to negative. These occur at the beginning (0 degrees), the midpoint of the wave (180 degrees), and at two additional points when it returns to zero (360 degrees, which is technically the same as 0 degrees, but the cycle can be considered continuous).

Therefore, recognizing that a complete sine wave goes through two complete oscillations (positive and negative), we can conclude that the voltage crosses zero at four distinct points within that single cycle. This understanding solidifies why the answer indicates there are four points where the voltage equals zero.