The present invention provides an electric pot comprising a first light source, a second light source, an image sensor and a processor. The first light source and the second light source respectively generates first light having a first wavelength and second light having a second wavelength. The first light generates a first light pattern on the surface of liquid, and the second light generates a second light pattern on the surface of solid in the liquid. The processor determines a liquid level of the liquid based on the first light pattern and determines a solid height of the solid based on the second light pattern.