These are both clever, but different physics. The toaster uses metallic elasticity (and a subsequent distortion) due to heat, and the rice cooker uses the heat-

These are both clever, but different physics. The toaster uses metallic elasticity (and a subsequent distortion) due to heat, and the rice cooker uses the heat-induced disappearance of magnetism to disengage a switch. (I have one of those toasters, and they’re very pretty and charming to see work.)