Abstract: A sun heat radiation sensor is provided having a plurality of display areas each of which comprises a different, heat activatable liquid crystal composition. The liquid crystal compositions are selected so that the display areas provide a quantitative visual indication of the sun heat radiation sensed by the sensor. The sensor may be applied to a container for sun-screening substances, e.g. typically to a lid of the container.

Abstract: Electrical apparatus for providing an indication of the level of the contents of a container comprises a temperature sensing unit, means for mounting, e.g. detachably, the temperature sensing unit against a container wall and visual and/or audible indicator means. The temperature sensing unit comprises a temperature sensing circuit including at least two spaced apart temperature sensors and an indicator circuit for energizing the indicator means. In use, energization of the indicator means occurs when the temperature sensors detect at least a minimum temperature difference.