Chapter 35, Problem 59A

Obtain several drinking straws. Take a deep breath and then fully exhale through one of the straws. Note the time it takes to do this. Repeat, fully exhaling through a pair of straws side by side. Can you exhale in less time? Try with three side-by-side straws. How does this relate to resistors in parallel in electric circuits?

To determine

The method for exhaling of air through straw becomes the same as the resistors in a parallel circuit.

Explanation of Solution

Introduction:

The inhale or exhale of the air through the straws occurs due to the pressure. The amount of air divides between the different straws if many straws are used.

The flow of air in the straw due to pressure is the same as the flow of electrons in the wire due to voltage. If the straws are connected in parallel, then the air passes from different straws and the amount of total air inhaled or exhaled is equal to the sum of air through each straw. The pressure across each straw is the same, so the same time is needed for exhaling.

The straw, air, resistance and pressure are analogous to wire, current, resistors and voltage of an electric circuit.

Conclusion:

The exhale of the air through different straws is the same as the resistors in a parallel circuit because the flow of air through a straw due to pressure is analogous to the flow of current through the circuit due to voltage.