- #1
wcjy
- 73
- 10
- Homework Statement
- Determine the current I (in Amperes) in the circuit below using nodal analysis.
- Relevant Equations
- -
Ans: 0.123A
Tried mesh analysis and got it but didnt for nodal analysis
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40I is from the current controlled voltage source. Isn't 40I in volts?haruspex said:40I-V_{0}? Subtracting a voltage from a current?
The rotated square (diamond) symbol with '+ -' is a controlled voltage source.haruspex said:40I-V_{0}? Subtracting a voltage from a current?
Can't see a problem. I also get I = 0.112(335)A and (for information) = 5.28(634) V. If you plug these values into check, you find that they give correctly balanced currents. Are you certain the answer should be 0.123A?wcjy said:
the system said the correct answer was 0.123. But anyways thanks, many people got 0.112 also. probably the answer is wrong. Gonna check with my professor.Steve4Physics said:Can't see a problem. I also get I = 0.112(335)A and (for information) = 5.28(634) V. If you plug these values into check, you find that they give correctly balanced currents. Are you certain the answer should be 0.123A?
You could post your mesh analysis for checking. But purple on a black background is pretty eye-unfriendly and probably puts a lot of people off. (Typed-up using Latex is the preferred method.)
Ok, I'd never come across that concept.Steve4Physics said:The rotated square (diamond) symbol with '+ -' is a controlled voltage source.
https://1.bp.blogspot.com/-VWAqITUrvhA/UY-k_NBxwfI/AAAAAAAAAUM/BPVlWJIFgXQ/s1600/sources.png
You can tell it's a voltage source because the '+ -' indicates polarity (as opposed to an arrow for a current source indicating current's direction).
'40I' indicates the output-voltage is numerically (in volts) 40 times the value of the current labelled 'I' (in amps) on the diagram.
haruspex said:40I-V_{0}? Subtracting a voltage from a current?
Yes. Also, it's in series with a resistor, which doesn't make a lot of sense for a current source.Steve4Physics said:You can tell it's a voltage source because the '+ -' indicates polarity (as opposed to an arrow for a current source indicating current's direction).
True, but by convention the units are usually omitted from the diagram and are assumed to be appropriate for the "conversion" implied by the sensed value and resulting output of the controlled source.haruspex said:Ok, I'd never come across that concept.
But the correct way to specify its value would be with units, namely, as 40IΩ.
yea the answer is wrong!rsk said:This is not something covered on the courses I teach but I was intrigued so decided to try to find out how to do such problems and have a go.
Perhaps not surprisingly, I can't get 0.123A as an answer. However, I'm wary of suggesting that's because the answer is wrong until I know for sure.
Please, @wcjy - it would be great if you could confirm one way or another when you ask your prof. Thanks :)
To determine the voltage at each node using nodal analysis, you will need to follow these steps:
Nodal analysis is a method used to analyze complex circuits and determine the voltage at each node. It allows for a systematic approach to solving circuit problems and can be used to analyze circuits with multiple sources and resistors. It is also useful in identifying the current flowing through each branch of a circuit.
Yes, nodal analysis can be used to analyze circuits with any number of sources and resistors. The number of equations needed to solve the circuit will depend on the number of nodes in the circuit. However, it may become more complex and time-consuming as the number of sources and resistors increases.
Nodal analysis assumes that all the nodes in the circuit are connected by ideal wires, meaning that there is no voltage drop or resistance between nodes. This may not be the case in real-world circuits, which can affect the accuracy of the analysis. Additionally, nodal analysis can become more complicated and difficult to solve for circuits with a large number of nodes or non-linear elements.
Yes, there are other methods for solving circuit problems, such as mesh analysis and Thevenin's theorem. These methods may be more suitable for certain types of circuits or may be easier to apply in certain situations. It is important to understand the principles and applications of each method to determine which one is most appropriate for a given circuit problem.