Texas A&M University

PHYS 217

LAB 5: LORENTZ FORCE
Mohammad Shihab
Texas A&M University
College Station, TX 77843, US.
Abstract:
This report covers the magnetic force, better known as the Lorentz force. The experiment is heavily dependent on a
magnet apparatus, which consists of two magnets and two load cells. Initially, these load cells must be calibrated by
placing known weights on the apparatus and applying a voltage to a wire coil hanging through the length of the
apparatus. Once this calibration has taken place, an amperage can be conducted through the wire. By using the
relationship between the Lorentz force, current, and length of the wire, the strength of the magnetic field, B, may be
calculated.
Keywords: Magnet, Lorentz force, Current, Coil
1. Introduction
Explain here the goal of the lab and the general theory and physics concepts needed to achieve it. Include major
equations to be used in your analysis. It should take from a few paragraphs to half a page.
The goal of this lab is to further understand the magnetic force, known as the Lorentz force. In this lab, the task is to
find the strength and direction of the magnetic field of between the two magnets of the apparatus. Since the Lorentz
force relates current and force in the presence of a magnetic field, finding the Lorentz force can allow us to find the
strength of the magnetic field. In order to begin this process, the load cells of the apparatus must be calibrated by
applying a known force on them and recording the voltage output by the cells. In order to do this, an masses are
increasingly placed on them and the voltages are recorded. In order to find the force on the load cells from the masses,
the mass in kilograms is multiplied by gravity. The following simple equation can be used.
? = ?? Equation 1
Once the force applied and voltages output have been recorded, the following equation can be used for
the calibration of the load cells, where C1 and C2 are some constants and Voutput is the average output by
the two load cells.
??????? = ??? + ?? Equation 2
Once the constants of C1 and C2 are solved for, the equation can be rearranged in order to isolate F,
which will later be used for our Lorentz force. Finally, we need to be able to calculate the strength of our
magnetic field. In order to do this, we start with the equation of F= q*v*Bsin(θ). Since we know our coil
and the magnet are perpendicular to one another, theta is equal to 90, meaning sin(θ) becomes 1.
Rearranging this equation gives us the equation we can use to solve for the strength of the magnetic field,
as seen below.