Lesson: Motion of Straight Conductors in Uniform Magnetic Fields Physics • 9th Grade

In this lesson, we will learn how to relate the potential difference induced across straight conductors to their motion in uniform magnetic fields.

Lesson Plan

Students will be able to

use the formula to calculate induced emf, magnetic field strength, and magnitude and angle of velocity to magnetic field direction,
use calculated induced emf to determine current and resistance in a circuit,
qualitatively describe induced emf variations in straight conductors undergoing periodic motion within uniform magnetic fields.

Lesson Video

Sample Question Videos

06:09

Lesson Worksheet

Q1:

A 15 cm long conducting rod has a potential difference across it, as shown in the diagram. The rod moves through a uniform magnetic field at 0.32 m/s. The magnitude of the induced potential difference is 9.6 mV.

What is the strength of the magnetic field?

Which side of the field-containing region is the rod moving toward?

Q2:

A small aircraft flies at 150 m/s through a region where the strength of Earth’s magnetic field perpendicular to its wings is 35 µT. The wingspan of the aircraft is 12 m. What potential difference is induced across the aircraft’s wingtips?

Q3:

The circuit shown in the diagram contains a 4.5 V battery attached to smooth conducting rails. The ends of the conducting rails are attached to a 15 cm long conducting rod with a resistance of 2.5 Ω and a mass of 750 g. The circuit is within a 125 mT uniform magnetic field.

What is the magnitude of the acceleration of the rod?

What is the initial rate at which the potential difference across the rod decreases due to the emf induced across it because of its motion in the magnetic field? Give your answer in scientific notation to one decimal place.