## Shock Value B/Circuit Lab C

Jim_R
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### Shock Value B/Circuit Lab C

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GuyFromNowhere
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### Re: Shock Value B/Circuit Lab C

Hello, Shock Valuers! Super excited for this event this year.
Quick question about a Thevenin equivalent problem. At JS Gandora's circuit lab test at the test exchange, there is a Thevenin equivalent problem. Setting Node B as the ground, I used nodal analysis to get that Node A has voltage of 4 and node at the far right connected to the branches with 3 ohm, 1 ohm, and 2 ohm resistors (let's just call as node c) has 6 volts.
The answer says that the Thevenin voltage is 3/8 V. (The voltage diff between A and B) could someone set me straight here? On the bright side, I'm getting a correct Thevenin resistance.
Thanks.
tangentline
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### Re: Shock Value B/Circuit Lab C

@Guyfromnowhere:
I did the problem with both the node voltage and superposition methods and came out to 4V.
The resistance of thevenin is indeed 15/8 ohms.
As far as confirmation, I used a "test" load resistor of 1 ohms and compared the respective current/voltage drop of the thevenin circuit and the actual circuit on that branch are the same with a thevenin voltage of 4V
The closest I can get to 3/8 is ignoring the current source and getting 5/8 V...
Last edited by tangentline on September 29th, 2013, 6:47 pm, edited 1 time in total.
JSGandora
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### Re: Shock Value B/Circuit Lab C

I probably made an arithmetic mistake there, I made the answer key somewhat in haste. You are most likely correct.
GuyFromNowhere
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### Re: Shock Value B/Circuit Lab C

Okay, thanks so much! Just wanted to make sure!
Je suis K
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### Re: Shock Value B/Circuit Lab C

what should I know for the "Practical" section?
Jdogg
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### Re: Shock Value B/Circuit Lab C

Je suis K wrote:what should I know for the "Practical" section?
You should be able to take your knowledge on the "test" portion and apply that to "lab" like questions. But you should also know how to operate a voltmeter, read resistor values, etc....
For example you might be given a RC circuit and asked to solve for the Capacitor's capacitance given a voltmeter, a switch, and a stopwatch while knowing the resistor and voltage of the battery (assumed to be ideal for small loads).
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transcience
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### Re: Shock Value B/Circuit Lab C

Can anyone make a list of website to study from?
Je suis K
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### Re: Shock Value B/Circuit Lab C

How do we practice the "practical" section? Should I just try to light up a light bulb with a wire? I know last year at the wright state invitational they had a really difficult (at least to me and my partner) practical section. Any advice?
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### Re: Shock Value B/Circuit Lab C

Je suis K wrote:How do we practice the "practical" section? Should I just try to light up a light bulb with a wire? I know last year at the wright state invitational they had a really difficult (at least to me and my partner) practical section. Any advice?
Based off what I've seen, the practical section can be anything from the theoretical section except in real-life form. So, you still might have to solve problems, along with measuring, building, and following through certain directions. Although, read the rules to see what exactly you might see at competition. But be prepared for anything. Build series circuits, parallel circuits, combination of both, and other complex circuits. Use switches, resistors, variable resistors, etc. Measure everything you build, use Ohm's Law to find Voltage, Current, and Resistance. Build a circuit with a bulb and try to make the bulb the dimmest possible without it completely going out, and then try to make it as bright as possible. Repeat with a combination of bulbs, resistors, wire lengths, etc. Build an electromagnet, and even on one competition test you were supposed to build a simple motor based on materials given. Also, based on what you have, use different materials to build circuits. For example, get used to using a breadboard, and also alligator clips, and the "generic" copper wire. Just like any other practical lab event, practice helps the most.

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