Module 4

1. Module 4

1.14. Page 6

Lesson 2

Module 4—Magnetic and Electric Fields in Nature and Technology

Reflect and Connect

A photograph shows the aurora australis captured by NASA's IMAGE satellite and overlaid onto NASA's satellite-based “Blue Marble” image.

Image courtesy NASA

In the photograph, the aurora australis is seen in a distinctly circular pattern as it appears from space over Antarctica. The same pattern is observed over the arctic region. The circular pattern is related to the fact that the magnetic field exits and enters Earth near the geographical poles. These regions have a significant magnetic field passing vertically through the ionosphere. The magnetic field at these locations is also perpendicular to the motion of the charged particles in the solar wind.

Watch and Listen

Watch the video Lorentz Force to see how Earth’s magnetic field exerts a magnetic force on charged particles to create the aurora.

A photograph shows an old-fashioned picture tube television—an example of CRT technology.

Reflect and Connect

The cathode ray tube played a very important role in the process of scientific discovery. It was instrumental in determining the charge-to-mass ratio of an electron and, ultimately, the mass of an electron. It also continues to be used for the demonstration of electromagnetism, revealing the relationship between magnetism and electricity.

But it is much more than that. It is a perfect example of scientific knowledge leading to the development of new technologies. After the work of Thomson, the CRT went on to be used in all kinds of applications. Most notable is the tube TV and computer monitor.

Save your responses to the following questions in your course folder.

RC 1. Explain how the television tube uses CRT technology to produce a moving colour picture.

RC 2. Describe the role of the electron gun and the magnetic field in tube televisions and explain why television sets don’t operate on batteries.

RC 3. Describe why cathode ray technology is destined to be a thing of the past.

Module 4: Lesson 2 Assignment

Remember to submit the Module 4: Lesson 2 Assignment to your teacher.