Chapter 10

Exercises

6. The needle is not pulled towards the north side to the bucket because the south pole is also pulling in the other direction. The net force is zero.

8. Moving electrons are deflected from their path by magnetic fields. A magnet held in front of a TV picture tube deflects the electron from its proper path causing it to strike the wrong portion of the screen.

10. The paper clip pulls on the magnet with the same force that the magnet pulls on the paper clip (Newton's 3rd Law). If this is true, why then does only the paper clip moved by the magnetic field when they are placed close to one another?

11. The iron ship becomes magnetized as it is built. Any magnetic reading then taken on or near the ship will be affected by this field. Corrections can only be made if its orientation while manufacturing is known.

12. The electric field changes speed, the magnetic field changes direction.

20. When the ground shakes, inertia of the suspended massive magnet tends to resist such shaking. But the coils are fixed to the earth and shake relative to the magnet. Motion of the coils in a magnet field induces an current.

24. A transformer is like a lever in that it can increase voltage at the expense of a current drop and vice versa, just as a lever can increase the force applied to lift an object at the expense of lost distance moved and vice versa.