The equation you provided is used to calculate the equivalent resistance ($R_{\text{eq1}}$) of three resistors ($R_1$, $R_2$, and $R_3$) that are connected in parallel.

Explanation:

When resistors are connected in parallel, the reciprocal of the equivalent resistance is the sum of the reciprocals of the individual resistances. The formula is:

$\frac{1}{R_{\text{eq1}}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}$

To find the equivalent resistance $R_{\text{eq1}}$, you would take the reciprocal of the sum of the reciprocals:

$R_{\text{eq1}} = \frac{1}{\left(\frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}\right)}$

Would you like more details or have any questions?

Here are five related questions:

1. How do you calculate the equivalent resistance for resistors in series?
2. What happens to the total resistance when more resistors are added in parallel?
3. How does the current distribute across resistors in parallel?
4. Can you explain the concept of a voltage divider in parallel circuits?
5. How would you solve for $R_{\text{eq1}}$ if only $R_1$ and $R_2$ are given?

Tip: In parallel circuits, the equivalent resistance is always less than the smallest individual resistance in the network.