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Power Measurement – Watts , dBm and conversion

September 28th, 2010 Leave a comment Go to comments


Most of us know that Watts is a unit of expressing power or the amount of the work done per unit of time. Electrically, One watt is defined as the amount of work done when one ampere of current is flowing through an Electric Potentiall difference of 1 Ampere.

In other words

P = VxA

If V is the voltage difference between a resistor of value R, then the wattage accross the resistor is given by

P = V*V /R

Example :- Find the wattage consumption accross a bulb of resistance 50 Ohm, if the voltage of 100 Volt is applied accross it.

Answer :- The wattage consumption is given by

P = V*V / R

Here,

V = 100 V
R = 50 Ohms,

So, P = 100 x 100 / 50
= 200 Watts

Many electricity companies report their power generation capacity in Megawatts. One megawatt is equal to 1 million watts.


RF and other electric design engineers use another unit of power consumption. It is a logarithmic measurement. Here is the formula to convert a power P into dBm

P(dBm) = 10 log10(p/p0)

P is the power in watts and P(dBm) is the power in dBm. Here p0 isequal to 1mW or 1×10-3 Watts. You may also use some online calculators to Calculate dBm from watts and vice versa.

Starred Reviews is glad to provide you analysis of the trusted calculators and online tools used by mathematicians and scientists. Feel free to post your comments below.

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