Physics Ohm Law
Experiment No: EM-1 Title: Ohm’s Law, Meters, Resistivity
I Purpose:
The basic of simple electrical circuits and measurements is learned. Also, investigating the dependence of the resistance of a wire on its length, cross-sectional area, and the material of which it is made. By examining electrical resistance (R) through a metal conductor, the voltage (V) and current (I) through the conductor, the following principles will be demonstrated:
1.) Ohm’s Law
2.) Dependence of resistance (R) on the length (L), cross-sectional area (A) and electrical resistivity (ρ) and volt, (V).
II Procedure:
Apparatus: DC power supply, milliammeters and ammeters, voltmeters, SPST switch, a “fused” connector, a 2-meter slide wire resistance, and mounted resistance spools.
Variation of V and I, with R held constant
1 Connect the apparatus as shown in the Figure below, attaching the voltmeter last.
Figure 1
2 Set the power to 4 volts. To begin with, set the voltmeter on the 0-5 volt rang and the milliammeter on the 0-1000 ma range.
3 Take a series of simultaneous voltage and current readings for currents I: 75, 150, and 225 milliamps.
4 Create a table and observe the value of the resistance and see if there is any constant.
Variation of V along a resistance wire, I constant
1. Connect the apparatus as shown in the Figure below.
Figure 2
2. Measure of V across various lengths L of the 2-meter wire between the 0 cm end and other points where the KEY is placed.
3. Measure and record the voltage V and the current I for lengths L of 20 cm, 50 cm, 80 cm, 120 cm, 150 cm, and 200 cm.
4. Calculate the resistance R, using Ohm’s Law for the length of wire for each case, and add the results to a table.
5. Graph the R’s versus the L’s.
III Data/Calculations/Results Variation of V and I, with R held constant
I1= 75 milliamps
V= 0.52 volts
I2= 150 milliamps
V= 1.03 volts
I3= 225 milliamps
V= 1.70 volts
Variation of V along a resistance wire,
I Purpose:
The basic of simple electrical circuits and measurements is learned. Also, investigating the dependence of the resistance of a wire on its length, cross-sectional area, and the material of which it is made. By examining electrical resistance (R) through a metal conductor, the voltage (V) and current (I) through the conductor, the following principles will be demonstrated:
1.) Ohm’s Law
2.) Dependence of resistance (R) on the length (L), cross-sectional area (A) and electrical resistivity (ρ) and volt, (V).
II Procedure:
Apparatus: DC power supply, milliammeters and ammeters, voltmeters, SPST switch, a “fused” connector, a 2-meter slide wire resistance, and mounted resistance spools.
Variation of V and I, with R held constant
1 Connect the apparatus as shown in the Figure below, attaching the voltmeter last.
Figure 1
2 Set the power to 4 volts. To begin with, set the voltmeter on the 0-5 volt rang and the milliammeter on the 0-1000 ma range.
3 Take a series of simultaneous voltage and current readings for currents I: 75, 150, and 225 milliamps.
4 Create a table and observe the value of the resistance and see if there is any constant.
Variation of V along a resistance wire, I constant
1. Connect the apparatus as shown in the Figure below.
Figure 2
2. Measure of V across various lengths L of the 2-meter wire between the 0 cm end and other points where the KEY is placed.
3. Measure and record the voltage V and the current I for lengths L of 20 cm, 50 cm, 80 cm, 120 cm, 150 cm, and 200 cm.
4. Calculate the resistance R, using Ohm’s Law for the length of wire for each case, and add the results to a table.
5. Graph the R’s versus the L’s.
III Data/Calculations/Results Variation of V and I, with R held constant
I1= 75 milliamps
V= 0.52 volts
I2= 150 milliamps
V= 1.03 volts
I3= 225 milliamps
V= 1.70 volts
Variation of V along a resistance wire,