The bandwidth of a single frequency sine wave is zero.
A sine wave consists of a single frequency component, and its waveform repeats itself indefinitely. In the frequency domain, the sine wave is represented by a single spike at a specific frequency. Since there are no other frequency components present, the bandwidth of a single frequency sine wave is considered to be zero.
Bandwidth refers to the range of frequencies occupied by a signal. For a single frequency sine wave, there is no range of frequencies, as it only contains a single frequency.