The amount of light given out or produced by an electric lamp — bulb, striplight or fluorescent tube — depends on the type of lamp and its wattage. The light produced is measured in lumens and a bulb or tube of a given wattage produces an average output of so many lumens. This will continue throughout most of its life.
Equally important is the number of lumens produced for each watt consumed, so it is usual to say, when comparing types, that a bulb or tube produces so many lumens per watt. The more the lumens per watt, the higher the efficiency of the lamp. Read the rest of this entry »
Many household appliances have some means of governing the temperature at which they operate. Examples include the regulation of high temperature ovens and heaters by switching elements on or off and, at the other end of the scale, the control of low temperatures in refrigerators and freezers by turning the compressor motor on or off.
A thermostat is an automatic device for regulating temperature. They range in type from the simple single action switch, which turns off or on at one pre-set temperature, to the fully adjustable type, which can be adjusted within a given range. Read the rest of this entry »
