Question

Which model below represents electric field lines attracting?
a. b. c. d.
12. A charged balloon is placed near the wall. This attracts the protons in the wall while
repelling the walls electrons. This is an example of ...
a. conduction b. conductor c. induction d. Friction
13. A person walks across the carpet, rubbing their feet. Next, they touch the doorknob,
transferring electrons into the doorknob. Which statement demonstrates conduction?
a. Walking across the carpet
b. Touching the doorknob
c. No conduction was demonstrated.
14. An electrically charged metal rod touches a neutral metal ball. Which statement best
describes what will happen next.
a. The protons within the rod will be transferred into the metal ball and spread out evenly across
the metal ball.
b. The electrons within the rod will be transferred into the metal ball and stay in a central
location.
c. The protons within the rod will be transferred into the metal ball and stay in the central
location.
d. The electrons within the rod will be transferred into the metal ball and spread out evenly.
15. Magnets can be temporary or permanent. Give an example of each one.
Permanent magnet:
Temporary magnet:
Section 4: Introduction to Waves.
16. A student was listing the electromagnetic wave from the weakest to the strongest. What
mistake did she make?
Here her list in order: Radio, Microwave, Visible light, Infrared, Ultraviolet, Gamma

Answer 1

For question 1 I don’t have the figures, so I can’t pick a, b, c or d. Upload or describe the four models and I’ll pick. Meanwhile, the rule to use: field lines point away from positive and toward negative charges. “Attracting” between opposite charges is shown by lines going from the positive toward the negative (converging and terminating on the negative).

12. c. induction
- The balloon induces charge separation in the wall (no contact), attracting opposite charges.

13. b. Touching the doorknob
- Conduction is transfer of charge by contact; the touch moves electrons to the knob.

14. d. The electrons within the rod will be transferred into the metal ball and spread out evenly.
- In a conductor electrons move and then redistribute over the connected conductors. (Protons in the metal lattice do not move.)

15. Examples
- Permanent magnet: refrigerator magnet (or a neodymium bar magnet, lodestone).
- Temporary magnet: an iron nail that becomes magnetic near a magnet (or an electromagnet when current is on).

16. The mistake: Visible light and infrared are out of order. Correct order from weakest (lowest frequency/energy, longest wavelength) to strongest (highest frequency/energy, shortest wavelength) is:
Radio < Microwave < Infrared < Visible < Ultraviolet < X‑rays < Gamma
(So visible should come after infrared; the student placed visible before infrared.)