3B: Electromagnetic Induction
PARTS LIST
PART / QUANTITY500 and 1000 turns coils / 1 ea. /
Transformer / 1 /
Signal Generator
(Also called function generator0 /
Galvanometer / 1 / Imgae not available
Power Supply / 1 /
Multimeter / 1 /
Compass / 1
Permanent Magnet / 1
3B: ELECTROMAGNETIC INDUCTION
PART I. Right Hand Rule
We will use the R.H.R. to find the winding direction of two Coils, one with 1000 turns and the others with 500 turns. After determining the winding direction, check your answer with the instructor. Results of the remaining experiment depend on the direction of the windings.
Connect the 500-turns coil to the dc power supply, as shown in the diagram. Make sure that port I is connected to positive and port II is connected to negative terminals of the power supply. Turn on the supply and apply approximately 1.0 volts to the coil. Using the compass, determine the direction of the induced magnetic field in the coil. To do so, bring the compass close to one end of the coil and notice the direction of the needle. If you place the compass at the other end of the coil, the direction of the needle should get reversed. Using R.H.R and noting the direction of current, determine the winding direction of the coil and write your answer in the data sheet. Repeat the procedure for the coil with 1000-turns. Winding for both of the coils are in the same direction.
PART II. Lenz Law
Connect the 1000-turns coil to galvanometer. Be sure that port I is connected to + and II is connected to -.
Take a small magnet and move its N pole in and out of the coil into the end marked I. You can use a compass to be sure of the poles of your magnet. Be careful not to peg the needle on the galvanometer. Predict the outcome of the actions outlined in Table I of the data sheet, do the experiment and write the correct answer in that table. You will not be penalized for incorrect predictions so do not alter your initial answers to the predictions.
PART III. Transformer
Make a transformer from two coils and connect the 500-turns coil to the signal generator (use the ground(-) and low W (+) plugs). Set the frequency to 100 HZ. Use the voltmeter (set to ~V, 20) to set the rms voltage of the AC generator to 1 volt. Connect the Voltmeter across 1000 turns coil and measure the voltage. Connect the voltmeter back to the 500 turns coil and set the rms voltage to 2 volts. Then measure and record the voltage across 1000 turns coil. Repeat the process for 3 and 4 volts across 500 turns coil. Plot V500 versus V1000 and do a linear curve fit. Repeat three times. Take an average of the slope. Print your graphs (reduce size, cut and paste onto one page, including the linear curve fit equation.) Record the average slope in your data sheet and answer:
What should be the slope of that curve? Is this a step up or step down transformer?
Briefly discuss your answer and results.