Question

In your reading for this module, you learned how the electric resistance of an object changes with cross-sectional area and with length. Let’s compare the flow of current in a circuit to the flow of water being sucked through a straw. For purposes of this comparison, the flow of water is equivalent to current and your suction strength is equivalent to voltage. Suppose you have four straws, as follows:

short and fat

short and thin

long and fat

long and thin

In your initial post to the discussion, respond to the following:

Which of the four straws described above gives the highest water current? Lowest?

Next, consider how water would flow through two other configurations of these same four straws:

One version where the four straws are taped end-to-end to make one long straw

The other version where all four straws are taped together side by side, so you would suck water through all four at the same time

Which of these two configurations produces the lowest current? Which produces the highest? Why?

Answer 1

1) Short and fat straw will have highest water current, long and thin straw will have lowest water current.

2) a. When we tape all straws together by end to end, water current will be restricted by long and thin straw and this configuration will have lowest water current.

b. When we tape all four straws together side by side, total water current will be the sum of water current of all individual straws and this configuration will have highest water current.