ignorantcircuitboi wrote:Although I know this is incorrect, during the competition we ended up putting the voltmeter in series with the various resistors. When put into parallel we got a reading of 0V but got positive values when in series... does anyone know why this would be the case?
ignorantcircuitboi wrote:I have a question. How do I solve the following question (like step by step process)?
I am given the following materials:
1 known resistor with resistance of 1,000 ohms
5 unknown resistors
a 3 V battery
How do I find the resistance value of each of the unknown resistors?
This was my approach, which turned out to be blatantly wrong:
First, I connected all the resistors in series. My thought process was that since I knew the resistance of one resistor, I could just use the voltmeter to find the find the voltage across the known resistor, and then I could find the current across that resistor. That current should be the same as the total current and the current across all the resistors because the circuit was in series. Using this, I could then measure the voltage across all the unknown resistors. Since I knew the current value, if I knew the voltage across the resistors, I could find all the resistance values.
Then, I put the leads of the voltmeter on the ends of the resistors (so I connected it in parallel). But the reading for the voltage was 0, so I could not find the value of the resistors. I think my thought process is wrong, does anyone know what I should do? Thanks!
ignorantcircuitboi wrote:I am not sure about all but the 3 out of the 5 I tested did so. I am fairly sure that all connections were solid as clean alligator clips were used.
satvik03 wrote:Uh what happens if you place the black lead closer to the voltage source and the red lead on the other side of the resistor (when measuring voltage across a resistor)? This should just give the negative value for voltage, but the magnitude should be the same right?
Pastaman202 wrote:At one of my invites, there was a switch that connected with 2 terminals, and you are given a capacitor, battery, lamp and resistor. The question was to set up a schematic diagram of how when the switch is connected to one terminal, the light bulb starts dim and get brighter and brighter, while the other starts bright and gets dimmer and dimmer. Does anyone know how to set this up? P.S. this was a div B test. Thanks!
a) this is an AC concept, will it be tested
b) if it is tested, how can I best understand it?
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