Download Hand Generator Lab

Hand Generator Lab
Name:
Period:
AP Physics
Basically, a generator works by rotating a wire loop through a magnetic field. As the flux through
the wire changes, an EMF is produced in the loop that can drive a current through any connected circuit.
In this lab we will attach a light bulb to the generator and measure how quickly we must turn the
generator to produce different amounts of EMF.
Materials: Hand Generator
Ammeter
Voltmeter
Flashlight Bulb
Schematic diagram
Procedure:
0. Connect the materials as
shown in the schematic diagram.
In place of the switch shown by
the bulb, we will simply
disconnect and reconnect the
wire leading to the bulb.
Hook up the voltmeter to
measure voltages up to 5 V.
Connect the ammeter to read
currents up to 500 mA
Part A – No load
1. Disconnect the wire leading to
the bulb as shown in the picture.
2. Rotate the handle of the
generator so that the voltmeter
reads a constant 1.0 V.
3. Use the stopwatch to time 10
complete revolutions of the handle.
Record the time in the data table
4. Calculate the period of the
rotation (time for one rotation) and
the frequency (number of rotations per time)
Part B – Loaded
1. Connect the wire leading to
the bulb as shown in the
picture.
2. Rotate the handle of the
generator so that the voltmeter
reads a constant 1.0 V.
3. Read the current through the
bulb from the ammeter.
Record your result in the data
table.
4. Use the stopwatch to time
10 complete revolutions of the
handle. Record the time in the data table
Base
Wires
5. Calculate the period of the rotation (time for one rotation) and the frequency (number of rotations per
time)
Data Tables:
Part A – No Load
Voltage (V)
0.0
1.0
2.0
3.0
4.0
5.0
Time for 10 Revolutions (s)
∞
Period (s)
∞
Frequency (Hz)
0.0
Part B – Loaded
Voltage (V)
0.2
1.0
2.0
3.0
4.0
5.0
Current (A)
Time for 10 Revolutions (s) Period (s)
Frequency (Hz)
Analysis:
Part A – No Load
1. Graph the voltage produced as a function of the frequency of turning. Leave some extra room on the
x-axis for later work. Draw a line of best fit when you are done graphing.
2. Use your graphing calculator to find a best-fit equation for the graph. Record your equation near the
line, be sure to plug in appropriate variables for x and y in the equation.
Part B – Loaded
1. On the graph above, graph the voltage produced as a function of the frequency of turning for the
second set of data. Draw a line of best fit when the graph is complete.
2. Use your graphing calculator to find a best-fit equation for the graph. Record your equation near the
line, be sure to plug in appropriate variables for x and y in the equation.
3. On the graph below, graph the voltage produced in the generator as a function of the current flowing
through the circuit. Draw a line of best fit through the points.
4. Use your graphing calculator to find a best-fit equation for the graph. Record your equation near the
line, be sure to plug in appropriate variables for x and y in the equation.
Questions
1. How different are the lines for voltage as a function of frequency from the two different parts of the
lab? Why might they be different?
2. Looking at the graph of voltage as a function of current, explain the shape of the graph based on how
the generator and the light bulb (which is non-ohmic) behave in the circuit.