Mains Digital Joulemeter - Basic

can be used to measure the power and energy consumption of a wide range of mains devices (up to a maximum power of 3750 W).
The display shows values of voltage (V), current (A), power (W), frequency (Hz) and energy (kWh). It is straightforward to use, and simply pressing one of the buttons changes the display to show the quantity selected.
There are many useful activities on measuring power that can be done quickly in the classroom, for example, looking at the difference between ordinary and energy-efficient light bulbs, or at the power reduction when a computer is switched into standby mode. The monitor can also be used over longer periods of time to measure total energy consumption, for example, the energy needed to run a refrigerator and whether this depends on how full it is or on the temperature of the room.