You will need to use the Voltmeter and the Ammeter so select these Tools from th

Question

You will need to use the Voltmeter and the Ammeter so select these Tools from the Tools settings box on the right. It is convenient to see the values of the resistance of the light bulbs and the voltage of the battery so select “Show Values” from the Visual settings box on the right. In the figure below, we have shown the virtual DMM (used to measure voltage between the red and black probes) and an Ammeter dragged out into the blue workspace. In order to answer the questions below you will need to connect these in the PhET tutorial simulation, in the correct way, in order to answer the following questions. We have also added the numbered red dots to indicate specific points in the circuit which will be referred to in the questions below.

Q1 – What is the voltage difference, as you measure with the virtual DMM voltmeter, across the battery, i.e., the voltage difference between points 1 and 6?

Q2 – What are the voltage differences, as you measure with the virtual DMM voltmeter, across the light bulbs individually, i.e., the voltage difference between points 2 and 3, and then the voltage difference between points 4 and 5? Do these answers make sense? (Explain)

Q3 – What is the voltage difference, as you measure with the virtual DMM voltmeter, across a length of wire, e.g., the voltage difference between points 1 and 2?

Q4 – What is the current flowing in the wires, as you measure with the virtual Ammeter, before the current reaches the light bulbs, i.e. in the length of wire from point 1 to 2?

Q5 – What is the current flowing in the wires, as you measure with the virtual Ammeter, before the current reaches the second light bulb, i.e. in the length of wire from point 3 to 4?

Explanation / Answer

1) DMM reading = 9 volts

2) Req = R1 + R2 = 10 +10 ohms = 20 ohms

current = I = V / Req = 9 / 20 = 0.45 A

V2-3 = I * R1 = 0.45 *10 = 4.5 V

V 4-5 = 0.45 *10 = 4.5 V

3) 9-4.5 = 4.5 V

4 ) Iwire = V / Rwire  = 9 / Rw   ( Rw is not given , if resistivity is given then R = resistivity * length /Area )

5 ) current is constant in series connection i.e I = 0.45 A

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