CH21_PontilloB

Chapter 21: Magnetismtoc

Pre Lab 11/22/11
1. The objective is stated in the title. What is your hypothesis? a. This is an inverse relationship, as the distance increases, the magnetic field strength decreases. 2. What is the rationale for your hypothesis? a. The equation provided above proves that as the equation gets divided by a larger distance, the value of magnetic field strength decreases because it is being divided by a larger number. 3. How do you think you might test this hypothesis? a. Measure the distance and //m// and use this to solve for B. 4. Read the entire procedure through. 5. Design __data table(s)__ in order to record your observations __and__ calculations. Do this in Excel a post this draft on your wiki.

Make a Motor 11/30/11
media type="file" key="makeamotorvid.mov" width="300" height="300" Discussion Questions: 1. How does a galvanometer work? A galvanometer is used to detect and measure electric current. It has a pivoting coil of wire that is always in a magnetic field. The coil is attached to a thin pointer that traverses a calibrated scale and shows the measurement. When a direct current flows through the coil, it generates a magnetic field. The coil to pivot, will cause the pointer to point to a value that indicates the electric current.

2. Define motor and generator. A motor is a machine, especially one powered by electricity or internal combustion, that supplies motive power for a vehicle or for some other device with moving parts. A generator is a device that converts mechanical energy into electrical energy.

3. A motor is a device, which converts electrical energy into mechanical energy (motion). Explain how your motor does so. The electrical energy from the circuit, which is being pushed by the battery, flows through the coil which is part of the motor. When this electrical energy passes through the coil, a magnetic force is produced which spins the coil. This spinning of the coil is the mechanical energy, which was converted from the original electric energy.

4. Why does the one rotor support have only ½ of its insulation sanded off? If both sides of the rotor support were sanded down, then the coil would never spin because the magnet would keep pushing it back and forth. When we sand 1/2 of a rotor, this causes the current to be cut off due to the fact that the conductor path has been cut off. This allows the magnets to take no effect and as a result, gravity and momentum take over and allow the coil to spin. When it makes it turn, the circuit is once again connected and the process begins again.

5. How could the motor you built in be converted to a generator? Describe carefully what would have to be changed and what the result would be. A generator is the opposite of a motor in the sense that it converts mechanical energy into electrical energy. As a result, I could spin the coil with my hand. This would be the mechanical energy. This spinning would result in the circuit being connected. Once the circuit is connected, electrical energy is then being produced.