Question

You have a 100 ohm resistor. How

much resistance must you add in
parallel to the 100 ohm resistor to
create an equivalent resistance of
75.0 ohms?

Answer 1

R2 = 300 Ohms

Step-by-step explanation:

Let the two resistors be R1 and R2 respectively.

RT is the total equivalent resistance.

Given the following data;

R1 = 100 Ohms

RT = 75 Ohms

To find R2;

Mathematically, the total equivalent resistance of resistors connected in parallel is given by the formula;

`RT = \frac {R1*R2}{R1 + R2}`

Substituting into the formula, we have;

`75 = \frac {100*R2}{100 + R2}`

Cross-multiplying, we have;

75 * (100 + R2) = 100R2

7500 + 75R2 = 100R2

7500 = 100R2 - 75R2

7500 = 25R2

R2 = 7500/25

R2 = 300 Ohms