Product Sum

Substitution Algebra

Product Sum

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Product Sum Calculation

More as a practice of mathematics manipulation of formulas, product sum is included in these electrician math web pages.

When thee are two resistances in parallel, the total resistance is the product of the two resistance values divided by the sum of the two values.

For example, if there are two resistors in parallel that are, say, 4 ohms each. The product of 4 times 4 is 16 divided by the sum of 4 + 4 which is 8.

So 16 divided by 8 is 2. Or to use the formula for when all resistors are the same value, the value of any resistor - 4 ohms - divided by the number of resistors - 2 - equals 4 divided by 2 or 2. Got it?

Here's the formula:

Rt = R1 times R2 / (R1 + R2)

Find practice problems HERE.

Find audio support HERE.

Another neat calculation for resistors in parallel deals with a circumstance when they all have the same value.

The formula for determining resistance total when all resistors are the same value is the value of any one of the resistors divided by how many there are.

Rt = R1 / N

where Rt is resistance total, R1 is the value of a single resistor, and N is how many there are all connected in parallel.

Find practice problems HERE.

Find audio support HERE.

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