Abstract: A vacuum cleaner with a suction nozzle which is coupled to a handle on which a user of the vacuum cleaner can exert a pushing or pulling force for moving the suction nozzle over a surface to be cleaned. The suction nozzle is provided with an electrical drive for exerting a driving force on the suction nozzle, such that the pushing or pulling force to be exerted by the user is limited.According to the invention, the vacuum cleaner comprises a detector capable of measuring the pushing or pulling force, exerted on the handle and an electrical controller for controlling the driving force as a function of the measured pushing or pulling force. The controller controls the driving force in such a manner, for example, that the measured pushing or pulling force remains substantially zero. It is thus possible for the user to move the suction nozzle effortlessly over the surface to be cleaned.

Abstract: Hair dryer with remote sensing of the moistness of the hair by means of a detector which compares the amount of radiant energy in two absorption bands in the spectrum of light emitted by an infra red source and reflected by the hair. One of the absorption bands is caused by water in the hair. The amount of radiant energy in this absorption band changes significantly during the drying of the hair. The other absorption band is caused by keratin in the hair. The energy in this band changes to a much smaller extent during the drying of the hair. The intensity ratio of the two bands is an indicator for the moistness of the hair and can be employed to control the temperature and/or the air flow of the hair dryer.