EFFICIENCY (%?) = Useful energy transfer/
Total Energy Transfer
I.e 100 Watts go into a lightbulb. Only 5 Watts get's converted into light = 0.5 or 5% efficiency.
Energy Transferd (kWh) = Power (kW) x
I.e 7kw Shower, is on for 3 hours. 7x3 = 14 kWh
Cost of Electric
Total Cost = Number of kWh (kWh) x
Cost Per kWh (hours)
I.e a family uses 500 kWh, each one costing 5p. 500x5 = 2500p or £25
WaveSpeed (m/s) = Frequency (hz) x
I.e A wave has a frequency of 3000Hz, and a wavelength of 1 metre.
3000 x 1 = 3000 m/s
Power (W) = energy transferred (J) ÷ time taken (s)