WH, AH , V
I would like to understand how to read those numbers and see how many times a power bank charger can recharge my phone or laptop.
In: 0
Wh is Watt-hour. Its a unit of energy. 1 W = 1 J/s , 1 J/s × 3600s = 3600 J = 1 Wh is not a large unit of energy so we often use 1 kWh = 1000 Wh.
Ah or Amper-hour is a unit of charge. 1 A = 1 C/s , 1 C/s × 3600s = 3600 C (Coulomb) = 1 Ah. 1 C is a gigantic amount of charge so usually we use 1 mAh = (1 Ah)/1000.
V is voltage. Its the potential of an electric field. Potential is the Coulomb force action on a 1 C charge at a given point. V is N/C the amount of froce that acts on a unit of charge. And the potential difference between two points is also measured in V. This is the voltage you use in Ohm’s law R=U/I, U is the potential difference or voltage R is the resistance and I is the current.
W is just Watt its power, energy/time J/s. If you got a heater and its 500 W power it means it gives heat to water for example at a rate of 500 J/s.
Heating water looks like this Q = c×m×T where Q is the energy c defines how easy it is to warm up the thing m is the mass of the thing and T or usually delta T is the temperature increase we want. So lets go with 0°C->100°C and 1 liter or 1 kg water. c=4200 J/kg°C for water so that means: 4200 × 1 × 100 = 420000 J. We can do 500 J/s so 420000 J / 500 J/s = 840s so 14 minutes. Electroc kettles are around 2000 W that gives about 3 minutes.
Latest Answers