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Ohm’s law Calculator

 

You can find the calculator at the bottom of this article. We’ll start with an introduction to this topic. 
 
The Ohm’s law (after Georg Ohm) defines the relationship between voltage (V), current (I) and resistance (R). Power (P) relationships appear as a logic consequence of the others.

One ohm is the resistance value through which one volt will produce a current of one ampere. The Ohm’s formula is   V = IR.
     

Voltage (V) is the difference in electrical potential between two points in an electronic circuit, and it is measured in volts (V). 

Current (I) is a flow of electrons on a conductor, and it is measured in amperes (A). 

Resistance (R) determines how much current will flow through an electrical device. Resistors are used to control or limit voltage and current levels. A high resistance will allow a small current to flow. A low resistance will allow a larger current to flow. Resistors are measured in ohms. 

Power (P) is the voltage multiplied by the current, and it’s measured in watts (W). 

Ohm's law pie chart - electrical calculations 

Ohm’s law Pie Chart

Electrical Calculations 

Let’s say that a 12V car battery is connected to a 3 ohm light bulb. What is the voltage measured at the light bulb? 

We can use our calculator and enter 

V = 12.0 V
R = 3.0 ohms 

We get           

I = 4.0 A 

Parallel Resistors 

Our calculator can also be used to find out the equivalent resistor of up to three resistors in parallel. For example, three 20-ohm parallel resistors are connected across a 120 V power source. What is the current of this circuit?
 

We use the section on parallel resistors and enter 

R1 = 20 ohms
R2 = 20 ohms
R3 = 20 ohms 

we learn that the equivalent resistor is Req = 6.7 ohms. 

Now, we use the formula I = V/R and enter the known values of voltage and resistance 

V =   120 V
R =   6.7 ohms

and we discover that the total current flowing is I = 17.91 amperes.


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Parallel Resistors

R1 = ohms
R2 = ohms
R3 = ohms

Req = ohms

V = I R

I = A
R = ohms

V = V

V = P/I

P = W
I = A

V = V

V = sqrt( PR )

P = W
R = ohms

V = V

I = V/R

V = V
R = ohms

I = A

I = P/V

P = W
V = V

I = A

I = sqrt( P/R )

P = W
R = ohms

I = A

R = V/I

V = V
I = A

R = ohms

R = V2/P

V = V
P = W

R = ohms

R = P/I2

P = W
I = A

R = ohms

P = VI

V = V
I = A

P = W

P = V2/R

V = V
R = ohms

P = W

P = I2R

I = A
R = ohms

P = W



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