Resistance Box

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  • Topic: Ohm's law, Electrical resistance, Electric current
  • Pages : 3 (641 words )
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  • Published : October 6, 2011
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Measurement of Electrical Resistance and Ohm’s Law|
Physics Lab 204.001|
Yewande Adeniyi|

1. Connect the ammeter A, the voltmeter V, and the power supply PS to the Resistance Box. The basic circuit supply is series with a resistor. To measure the current in the resistor, the ammeter is placed in series. To measure the voltage across the resistor, the voltmeter is placed in parallel. 2. Vary the current through resistor R1 in steps of .125A to .500A. For each specified value of the current, measure the voltage across the resistor and record the values in Data Table 1. The resistors will heat up and may be damaged by allowing current in them for long periods of time. Measurements should be made quickly at each value of the current. APPLY VOLTAGE ONLY WHEN DATA ARE BEING TAKEN. 3. Repeat Step 2 for each of the 5 resistors. For each resistor the ammeter must be in series with that resistor and the power supply, and the voltmeter must be in parallel with the resistor. Record all values in Data Table 1. 4. Connect the first Resistance Box to the second Resistance Box to measure the equivalent resistance of the combination. Use two values of current, 0.250A AND 0.500A, and measure the value of the voltage for each of these values of current. Record the voltage in Data Table 2. 5. Measure the voltage across the combination of R1 and R2 in series for currents 0.250A AND 0.500A and record the values in Data Table 2. 6. Connect Resistance Box 1 and 2 in parallel and measure the voltage across the combination for currents value of 0.250A and 0.500A and record in Data Table 2. APPARATUS

R(Ω)| 40Ω| 100Ω|
I(A)| VRI(V)| VR2(V)|
.125A| 0.49V| 3.86V|
.250A| 1.01V| 8.02V|
.375A| 1.50V| 12.05V|
.500A| 2.02V| 16.30V|
| R1| R2|
RTHEO| 40Ω| 100Ω|
REXP| 4.064Ω| 33.1Ω|
% ERROR REXP| 8.99%| 66.9%|
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