A2L Item 200

• Description: Identify the correct statement(s) regarding a charged particle in a region having both an electric and magnetic field.
• Goal: Distinguishing components of the Lorentz force
• Source: 283 - effects of magnetic force
• Keywords: Electric Field, Electromagnetism, Magnetic Field, Work

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The question for students:

A charged particle moves into a region containing both an electric and magnetic field. Which of the statements below are true?

1. The particle cannot accelerate in the direction of B.
2. The path of the particle must be a circle.
3. Any change in the particle's kinetic energy is caused by the E field.

1. Only A
2. Only B
3. Only C
4. Both A&B
5. Both A&C
6. Both B&C
7. All are true.
8. None are true.

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Commentary for teachers:

Answer

(3) The only cases that most students see is the one having E and B perpendicular. As a result they discount the case of E and B parallel and think statement A is also true.

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