I teach AP Physics 1 & C, covering topics of kinematics, force, energy, momentum, rotation, oscillations, electricity & magnetism.
Your friend insists that a strong magnetic field is required to induce a current in a coil that has no battery. Describe one experiment that she and you can perform to observe that a strong magnetic field helps induce an electric current and two experiments where no current is induced even with a strong magnetic field. What should you conclude about your friend’s idea?
To check whether a light bulb permanently attached to a coil is still good, you place the coil next to another coil that is attached to a battery, as shown in Figure P18.4. Explain how or whether each of the following actions can help you determine if the light bulb is ok. (a) Close the switch in circuit A. (b) Keepthe switch in circuit A closed. (c) Open the switch in circuit A.
You need to invent a practical application for a coil of wire that detects the vibrations or movements of a nearby magnet. Describe your invention. (The application should not repeat any described in this book.)
Estimate the magnetic flux through the south- and west facing windows of a house in British Columbia, where Earth's $\vec{B}$ field has a magnitude of $5.8 \times 10^{-5} \mathrm{T}$ and points roughlynorth with a downward inclination of $72^{\circ} .$ Explain how you made the estimates.
You have the apparatus shown in Figure P18.14. A circular metal plate swings past the north pole of a permanent magnet. The metal consists of a series of rings of increasing radius. Indicate the directionof the current in one ring (a) as the metal swings down from the left into the magnetic field and (b) as the metal swings up toward the right out of the magnetic field. Use Lenz’s law to justify your answers.
"Your friend thinks that an induced magnetic field is always opposite the changing external field that induces an electric current. Provide a detailed description of a situation in which this idca would violate energy conscrvation.