Question

use the following information to answer the questions. an electromagnet is a type of magnet in which an item that is usually not magnetic, such as an iron nail, uses an electric field in order to become a magnet. a student builds an electromagnet using a battery, a plastic nail, and some thin insulated wire. the wire is wrapped around the nail 10 times and then connected to the battery. 1 what changes could the student make to increase the strength of the electromagnet? (a) select all that apply. there are three (3) correct answers. a replace the plastic nail with an iron nail b replace the wire with a wire that has less resistance c wrap more loops of the wire around the nail d remove half of the loops around the nail e increase the length of the wire f decrease the voltage of the battery (b) when creating the electromagnet, there were several possible dependent var_ mentioned. those variables included the resistance of the wire, the number of loops around the nail, and the type of nail. all of these changes would be made in order to test the strength of the electromagnet, which would be the constant var_ . if a student decides to compare various numbers of loops of wire around the nail, the voltage of the battery and the type of nail used would need to be independent va_

Explanation:

• Option A: Iron is a ferromagnetic material. Using an iron nail instead of a plastic nail allows the nail to become magnetized more effectively as it can be easily magnetized by the electric field, thus increasing the strength of the electromagnet.
• Option B: According to Ohm's law \(I=\frac{V}{R}\) (where \(I\) is current, \(V\) is voltage, and \(R\) is resistance). If the voltage of the battery (assuming it's constant) and we decrease the resistance (\(R\)) of the wire (by replacing it with a less - resistant wire), the current (\(I\)) in the circuit will increase. A larger current in the electromagnet (since the magnetic field \(B\propto I\) for a simple solenoid - like electromagnet) will increase its strength.
• Option C: The magnetic field \(B\) of a solenoid (which an electromagnet made by wrapping wire around a core resembles) is given by \(B = \mu_0nI\), where \(n=\frac{N}{L}\) ( \(N\) is the number of turns, \(L\) is the length of the solenoid). If we keep other factors (current \(I\), length \(L\) approximately constant if we just add turns without changing the length much) and increase \(N\) (by wrapping more loops), the magnetic field \(B\) (and thus the strength of the electromagnet) will increase.

• Option D: Removing half of the loops (decreasing \(N\)) will decrease the magnetic field (using the \(B=\mu_0nI\) formula, as \(n=\frac{N}{L}\) and if \(N\) decreases, \(n\) decreases for a fixed \(L\)) and thus the strength of the electromagnet.
• Option E: Increasing the length of the wire (assuming the wire is in series with the battery) will increase the resistance of the wire (since \(R=

ho\frac{l}{A}\), where \(
ho\) is resistivity, \(l\) is length, \(A\) is cross - sectional area). Using \(I = \frac{V}{R}\), an increase in \(R\) (for a fixed \(V\)) will decrease \(I\). A decrease in \(I\) will decrease the magnetic field (\(B\propto I\)) and thus the strength of the electromagnet.

• Option F: Decreasing the voltage of the battery (using \(I=\frac{V}{R}\), for a fixed \(R\)) will decrease the current \(I\). A decrease in \(I\) will decrease the magnetic field (\(B\propto I\)) and thus the strength of the electromagnet.

Answer:

A. Replace the plastic nail with an iron nail, B. Replace the wire with a wire that has less resistance, C. Wrap more loops of the wire around the nail