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# What Is the Expected Current in This Circuit Based on Ohms Law Physics Lab Report

1. Watch this video (Links to an external site.). It gives an overview of the lab kit (VERY helpful). Take out the components and play along if you like!
2. ⭐️ What is the voltage of your battery?
3. ⭐️ To make sure you don’t break the multimeter we’re going to calculate the minimum resistance that we can connect to the battery. If you want a maximum possible current of 150 mA, what is the smallest resistance you can attach to your battery?
4. ⭐️ Create Circuit 1(shown below) using a 20 ohm resistor, your battery, the switch (leave the switch open), and the Ammeter (which is the multimeter set up to measure current). Take a picture of your physical circuit setup and include it here.
NOTE: Always check the values of resistors before putting them in the circuit using the Multimeter in Ohmmeter mode.

$⟸$ Circuit 1

1. ⭐️ What is the expected current in this circuit based on Ohm’s Law?
2. ⭐️ What is the actual current when you close the switch? (don’t forget to open the switch after you measure)
3. ⭐️ Move the Ammeter in the circuit so that is between the switch and the resistor. What is the current now (when the switch is closed)?
4. ⭐️ How do the answers of #6 and #7 compare? Are the answers consistent with your understanding of current?
5. Remove the Ammeter and rebuild the circuit as shown below

$⟸$ Circuit 1 (without the Ammeter)

1. Watch this brief video on measuring voltage in a circuit (Links to an external site.).
2. ⭐️ Change the multimeter to Voltmeter mode (using the 2000 mV range). Close the switch. What is the voltage across (i) the battery, (ii) the switch), and (iii) the resistor?
NOTE: Remember the battery voltage is positive and the other ones are negative or zero .
3. ⭐️ What does the sum of the voltages add up to? Is it as expected? Explain.
4. Open the switch
PART II: 2 Resistor Series Circuit
1. Set up Circuit 2 shown below using a 100 ohm resistor and a 20 ohm resistor. This is 2 resistors in series.

$⟸$ Circuit 2

1. ⭐️ Calculate the expected equivalent resistance of this circuit.
2. ⭐️ Measure the actual equivalent resistance of this circuit. (make sure the switch is off for this part)
3. ⭐️ What do you expect the current to be (i) through the battery, (ii) between the resistors?
4. ⭐️ Measure the current at those two points. Is it as expected?
5. ⭐️ What do you expect the voltage drop across each resistor to be? Explain.
6. ⭐️ Measure the voltage across each resistor. Is it as expected?
7. Open the switch
PART III: 2 Resistor Parallel Circuit
1. Set up Circuit 2 shown below using a 100 ohm resistor and a 20 ohm resistor. This is 2 resistors in parallel.

$⟸$ Circuit 3

1. ⭐️ Calculate the expected equivalent resistance of this circuit.
2. ⭐️ Measure the actual equivalent resistance of this circuit. (make sure the switch is off for this part)
3. ⭐️ What do you expect the current to be through (i) the battery, (ii) the 100 ohm resistor (iii) the 20 ohm resistor?
4. ⭐️ Measure the current at those three points. Is it as expected?
5. ⭐️ What do you expect the voltage drop across each resistor to be? Explain.
6. ⭐️ Measure the voltage across each resistor. Is it as expected?
7. Open the switch
PART IV: Equivalent resistance of a 4 Resistor Circuit
1. We’re just using resistors and wires for this one: Make up your own circuit using 4 resistors (make sure to choose 4 resistors that aren’t too different from each other and don’t just put them all in series! )
2. ⭐️ Draw a circuit diagram. Include a picture of your circuit diagram here.
3. ⭐️ Calculate the expected equivalent resistance of this circuit. (using resistor addition formulas)
4. ⭐️ Measure the actual equivalent resistance of this circuit.