A liquid crystal layer is formed by filing the space between alignment films formed on two glass substrates, respectively, with a ferroelectric liquid crystal having spontaneous polarization. A shock wave generated in a shock wave source is applied to food such as an apple or tea leaves to soften or pulverize the food. 1 \u03bcm or more and less than 1 \u03bcm and comprises, as main component, a compound having at least one kind of element selected from C, N and O, and Ti and Al. Thereby, the water level sensing apparatus prevents unnecessary water supply and reduces energy consumption.