Household electrical appliances. Saving electrical energy
The voltage of the mains in our homes is 220 V (frequency 50 Hz in Uzbekistan). Voltage up to 36 V is considered safe for humans, above it is dangerous: never touch an electrical appliance with wet hands, never touch bare or damaged wires, never push a metal object into a socket. The power of appliances is shown in watts (W) or kilowatts (kW). Energy consumed E = N · t; it is convenient to measure it in kilowatt-hours (kWh): 1 kWh = 1000 W · 1 h = 3 600 000 J. For example, a 100 W bulb burning for 10 hours uses 100 · 10 : 1000 = 1 kWh. The consumption is measured by a meter. Ways to save energy: turn off unneeded lights, switch to efficient LED lamps — a 10 W LED lamp lights like a 60 W incandescent lamp — choose refrigerators and air conditioners of an energy-saving class, and do not leave appliances on standby. Safety: do not switch appliances on without an adult’s permission, pull a plug out by the plug body (not by the cord), do not use appliances in wet places; in case of fire or electric shock call an adult.
“Home energy audit”: pupils write the power (from the label) and daily hours of 5 appliances at home, calculate daily consumption in kWh and propose a way to save. Safety: look at appliances only with an adult, do not switch them on, do not touch plugs or sockets.