Lab Activity 11: Direction of Magnetic Fields Read the activity and obtain the required materials: two bar magnets, a sheet of paper, and a compass. Then answer the analysis questions when finished. (25 pts) Procedure Step 1: Place a bar magnet horizontally in front of you so that the north pole faces left. Step 2: Place a second bar magnet on a horizontal line and 5.0 cm away from the first. The north pole also should be facing the left. (Hint: If you used lined paper, it will be easier to align your magnets.) Step 3: Draw your setup on a sheet of paper. Be sure to label the poles. (4 pts) Step 4: Place a compass between the two magnets. Draw the direction the arrow is pointing. (2 pts) Step 5: Continue to move the compass to other positions, each time drawing the direction it points until you have drawn 15-20 arrows. (2 pts) Step 6: Repeat steps 4-6, this time with the two north poles facing each other. Analysis 1 . What did the red end of the compass needle typically point toward? (3 pts) Away from? (3 pts) 2. Why might some of the arrows not point to either location stated in the previous question? (6 pts) 3. Critical Thinking What you have diagrammed with your arrows is called a magnetic field. Recall what a gravitational field and an electric field are, and define magnetic field. (5 pts)Lab Activity 13: Making a Simple Electric Motor Read the activity and obtain the required materials: 1.5 V alkaline battery (C or D battery size), a small nail or drywall screw, one neodymium disc magnet slightly bigger in diameter than the head of the nail/screw (usually found in plastic toys), copper wire approximately 6 inches in length (can be shorter), and safety glasses. Then answer the analysis questions when finished. (25 pts) Procedure Step 1: Obtain the materials listed above. Wear safety glasses! Step 2: Magnetically attached the head of the nail to the magnet. Step 3: Hold the battery in one hand with its positive terminal pointing downward. Now bring the tip of the nail in contact with the positive terminal. The nail and magnet should hang from the positive terminal of the battery. Step 4: If your wire is coated, expose both ends by 1/2 inch. Hold one end of the wire to the negative terminal of the battery which touching the other end of the wire to the side of the magnet. Observe what happens. Step 5: Draw your electric motor on a sheet of paper or attach a picture. (5 pts) Analysis Describe the motion of the magnet when the wire makes contact with the battery and the magnet. (3 pts) What happens if you flip the magnet upside down? (3 pts) Now, what happens if you switch around the connections on the positive and negative terminal ends, so now the tip of the nail/screw is in contact with the negative terminal? (3 pts) 2. What forces act on the magnet and in which directions do they act? Explain. (6 pts) 3. How do you think the results would change if two magnets were used instead of one? Explain your reasoning. (5 pts)Lab Activity 15: Lasers and the Moon On three different trips to the Moon, the astronauts of Apollos 11, 14, and 15 left some rather unusual mirrors, called laser-ranging retro-reflectors, on the surface of the Moon. The mirrors from missions 11 and 14 consisted of 100 silica half-cubes called corner cubes, and Apollo 15 left behind a mirror that had 300 of these cubes. A corner cube is a unique kind of mirror that always reflects the light incident on it directly back at the source that produced the light. If you look into two mirrors that meet at a 90 angle, you can see this unusual effect. Scientists send laser light up through an optical telescope, in through the eyepiece, and out through the main mirror. By the time it reaches the Moon, the beam is almost six kilometers wide. Any light that hits the retro-reflectors is bounced directly back to the telescope and can be detected by the scientists. Scientists have used this technology to determine many interesting facts about both the Moon and Earth: The distance between the center of Earth and the center of the Moon is 385,000 km to an accuracy of one part in ten billion. The Moon is receding from Earth at a rate of about 3.8 cm per year. The Moon might have a liquid core. There are very small variations in the amount of time it takes Earth to make one complete rotation in a day. The various tectonic plates are drifting and we can measure their directions and speeds There are other ideas still being studied, and many more facts to be uncovered. It is important for us to understand that some investments in science may be of value for many years after they are performed. The first retro-reflector was placed on the Moon in 1969, and is still doing its job today. (25 pts) Procedure Step 1: Place two mirrors side by side so they meet at a 90 angle. Observe your reflection in the mirror. Step 2: Move around while looking into the mirrors. Step 3: Shine a flashlight into the mirrors. Analysis 1. Describe what you see reflected at the intersection of the two mirrors when you are stationary. (5 pts) 2 . Describe what you see reflected at the intersection of the two mirrors as you move about. (5 pts)3. Describe where the beam from the flashlight is reflected. (5 pts) 4. Does the beam behave differently when shone into the intersection? (5 pts) 5. How do you think scientists know that the Moon is moving away from Earth at a rate of about 3.8 cm per year? (5 pts)