Question

Which of the following is not a unit of distance?

• A. Ammeter
• B. Cubit
• C. Parsec
• D. Angstrom

Hint:

Three of the options are units of length. One of them is actually a measuring device, not a unit at all.

Answer 1

The Correct Option is A

This question is really about sorting instruments from units. Read the list again and separate the four words into two groups.

• Cubit: an old body based unit of length, roughly the length of a forearm.
• Parsec: a unit used by astronomers to measure huge distances between stars, close to 3.26 light years.
• Angstrom: a tiny unit of length equal to \(10^{-10}\) meter, used for the size of atoms and wavelengths of light.
• Ammeter: not a unit at all. It is a measuring instrument placed in a circuit to read electric current in amperes.

Three of the four choices are units of length, but the ammeter is a device, not a unit. So it does not belong with the rest, and it is the correct answer.