Question

The picture shows an experiment used to determine the effect of using more nails in the core of an electromagnet. Which of the following would make this a better designed experiment? Using a different number of batteries for each electromagnet. Using the same number of turns of wire for each electromagnet. Inserting an ammeter in each circuit between the battery and the nails. Using a different size battery for each electromagnet.

Answer 1

It's B. I saw it on a K12 answer key sheet online. :-)

Answer 2

Answer: Using the same number of turns of wire for each electromagnet.

The formula of magnetic field strength of a solenoid or electromagnet is,

`B= \mu n i`

Where, B is the magnetic field strength, μ is the magnetic permeability, n is the number of turns per unit length, and i is the current in the wires.

To study the change in magnetic field strength B, the current i, and number of turns per unit length should be same so that
`B \propto \mu` and we can study the change of quantity of iron as core.