ELECTRONICS: Finding the voltage?


P=100 watts
R=100 ohms

Find: Voltage

Kindly show all necessary and important solutions. Really need it. Thanks.

The formulas of Ohm's Law

Ohm's Law can be rewritten in three ways for calculating current, resistance, and voltage.
If a current I should flow through a resistor R, the voltage V can be calculated.
V = R × I

If there is a voltage V across a resistor R, a current I flows through it. I can be calculated.
I = V / R

If a current I flows through a resistor, and there is a voltage V across the resistor R. R can be calculated.
R = V / I

P = VI (P is Watts, V is voltage and I is Amps/current) basically we need more details.

For single phase divide your watts by the voltage to get amps. You'll find on your residential system that the 220 volt heater will draw 1/2 the amps that the 110 volt heater will at the same watts. Depending on the total watts used the 220 volt unit will allow you to go a size smaller on the circuit conductors.
If your concerned about voltage drop for a residential circuit, don't be unless it is an exceptionally long run. If you are concerned then consult any electrical formula book or put "voltage drop" in a google search engine. Hope this helps.
This is easy as PIE> P=I*E
P=I^2 * R, SQRT (100/100) = 1 amp
so P/1= 100 volts
ohms law baby

V = 100
Ohms law Power = V x I but V = I x R so power = I x I x R 100 = 100 X Ix I therefore
I = 1 ampere. V = 100
Power is also = V x V/R = 100 = V X V/100
Therefore v= 100
Start with Ohms Law: V = IR.

Let's solve for I ...

I = V/R.

Now, power is equal to voltage times current, or


Let's substitute (V/R) for I, and we get

P = V*(V/R), which is V²/R.

We can use this with the above parameters:

100 Watts = V²/(100 ohms)

V² = 10000, so V = 100 V.

I hope this was helpful.
The relationship between power voltage and resistance can be summarized in the formula P = V^2/R(where V^2 means V squared, V being voltage P being power and R being resistance). This is derived from P=VI and I=V/R which is a power equation and ohms law. Subsituting in your values of P=100 and R=100 you get


with algebra 100*100=V^2

take square root of both sides(more algebra)to get

V=100 volts
1 volt

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