# Homework Help: Need some help on these Physics Questions

1. Oct 29, 2012

### varld

1. If a bar magnet is broken into two pieces, how many magnetic poles are there?

2. A long straight wire carries a current in the direction shown in the following figure. At the point labeled A, is the direction of the magnetic field left, right, up. Down, into the page, or out of the page? What is the direction at point B? Explain.

3. Three long straight wires each carry identical current in the directions shown in the following figure. What is the direction of the net force on the wire at the right?

4. One of the Earth’s magnetic poles located in Antarctica. Is it a magnetic North Pole or magnetic South Pole?

5. Consider the case in which the north pole of a bar magnet is being moved away from a conducting cooper ring. Do the field lines created by the induced current point toward the bar magnet or away? Will this induced field pull back on the magnet or push it away? Explain.

6. In Chapter 10 we found that an infinite amount of energy is required to accelerate a massive particle to the speed of light. What does this imply about the mass of a photon?

7. Two students are discussing what happens when you turn down the rate at which electrons are fired at two slits. Tyson claims, “Because you still get an interference pattern even with only one electron at a time, each electron must interfere with itself. As weird as it sounds, each electron must be going through both slits.” Ulricht counters, “That’s crazy. I can’t be at class and on the ski slope at the same time. Each electron must pass through only one slit.” Which student is correct? Explain

8. In the two-slit experiment with photons, what type of pattern do you expect to obtain if you turn the light source down so low that only one photon is in the apparatus at a time?

9. Where would you most likely find the electron if it is in a quantum state with n = 3, L = 2, and M=-2 as shown in Figure 24-13?

10. Like light, electrons exhibit diffractions when passed through a single slit. Use the Heisenberg uncertainty principle to explain why narrowing the slit (that is, improving the knowledge of the electron’s position in a direction perpendicular to the beam) causes the diffraction pattern to get wider.

2. Oct 29, 2012

### haruspex

Too many questions in one post. Please follow the forum standards and show your own attempts at solution.

3. Oct 29, 2012

### Staff: Mentor

please place each question in a separate thread, please show the equations you think are needed to solve the problem and please show some work before we can help.