Question

a group of students builds an electromagnet by turning wire around a nail, and then connecting the ends of the wire to a battery. the students can hang some number of paper clips from the nail, as shown below. the students predict that increasing the number of turns of wire around the nail will increase the strength of the electromagnet. they plan an investigation to test their prediction. what should they select as the dependent variable for their investigation? choose 1 answer: a battery voltage b paperclip size c number of paperclips that hang from the nail d number of turns of wire around the nail

Explanation:

To determine the dependent variable, we recall that the dependent variable is what is being measured or observed and depends on the independent variable. Here, the students are testing how the number of wire turns (independent variable) affects the electromagnet's strength. The strength is indicated by how many paperclips it can hold.

• Option A (battery voltage) is a controlled variable (should be kept constant), not dependent.
• Option B (paperclip size) is also a controlled variable (should be consistent).
• Option D (number of wire turns) is the independent variable (the one being changed to observe its effect).
• Option C (number of paperclips) depends on the electromagnet's strength, which is affected by the number of wire turns, so it is the dependent variable.

Answer:

C. number of paperclips that hang from the nail