* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Ohm`s Law
Spark-gap transmitter wikipedia , lookup
Transistor–transistor logic wikipedia , lookup
Galvanometer wikipedia , lookup
Immunity-aware programming wikipedia , lookup
Integrating ADC wikipedia , lookup
Valve RF amplifier wikipedia , lookup
Josephson voltage standard wikipedia , lookup
Schmitt trigger wikipedia , lookup
Operational amplifier wikipedia , lookup
Wilson current mirror wikipedia , lookup
Power electronics wikipedia , lookup
Opto-isolator wikipedia , lookup
Voltage regulator wikipedia , lookup
Power MOSFET wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Surge protector wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Electrical ballast wikipedia , lookup
Rectiverter wikipedia , lookup
Current source wikipedia , lookup
Name ________________ OHM'S LAW Objective: To verify Ohm's Law Apparatus: 100 ohm and 220 ohm resistors, 1 ohmmeter, 1 ammeter (0-220 mA DC), 1 voltmeter (0-15 volts), 1 DC power supply, conducting wires, graph paper Introduction: Ohm's Law states that the voltage across a resistor is directly proportional to the current through the resistor. This relationship is expressed by the equation: V = IR where V = potential difference across the resistor (volts) I = current through the resistor (amperes) R = resistance of the resistor (ohms) Figure 1 Procedure: 1. Measure the "100” ohm (brown-black-brown) resistor using the ohmmeter: Ohms. Measure the "220" ohm (red-red-brown) resistor using the ohmmeter: ohms. These are the actual and theoretical values that you will use in the lab. 2. Connect the "100" ohm resistor in series with the ammeter and the power supply. Connect the voltmeter across both the resistor and ammeter as shown in Figure 1. 3. Do not turn on the power supply before the instructor has checked your circuit! 4. 2 For safety, make sure that the voltage knob is turned to its lowest position. Then turn on the power supply. 5. Set the voltage to one volt. Read the ammeter. Record the voltage and current in Table 1. 6. Repeat step 5 for a voltage setting of 2 volts, 3 volts, etc. up to 8 volts. DO NOT EXCEED 8 VOLTS! 7. Record the voltage and corresponding current in Table 1. 8. Convert the current readings from milliamps to amps. Data Table 1 (“100” ohm resistor) Voltage (volts) Current (mA) Current (A) 9. Using Excel, plot a graph of Voltage (y-axis) vs. Current (x-axis). 10. Find the best fit line and include it on the graph. From it, determine the slope of the line. Slope of line, which is equal to the resistance R: __________ Ohms 11. Calculate the percent error. A = Actual value, E = Experimental value. % error = A - E X 100% = A 3 12. Repeat steps 1-8 for the “220 Ohm” Resistor Data Table 2 (“220” ohm resistor) Voltage (volts) Current (mA) Current (A) 13. Using Excel, plot a graph of Voltage (y-axis) vs. Current (x-axis). 14. Find the best fit line and include it on the graph. From it, determine the slope of the line. Slope of line, which is equal to the resistance R: __________ Ohms 15. Calculate the percent error. A = Actual value, E = Experimental value. % error = A - E X 100% = A 4 Questions: 1. State in your words the exact meaning of Ohm's Law. 2. If we completed an experiment where the voltage was kept constant but we kept changing the resistors, what changes if any would we see in the current? Explain your choices.