Labelling Nodes: A Guide for Electronics Lab

[Altairs]

Homework Statement

This is not a homework question but I still posted it here so that no one has any problems...

Today we had Electronics Lab and our teacher gave us the first lecture how to write a basic program for PSpice. She gave a circuit and asked us to write the program for it. (attached as picture). The problem came when she asked a mini-viva kinda thingy. She asked that what will you take at the tail of current source. +ive or -ive ? and why ? And guess what, no one knew the ans. Because there were just two possibilities so people took the signs randomly (in the hope that 50% chance will come out in their favor). And worst, she said that she will give the answer in next class which is a week away.

Homework Equations

Attached. Kindly identify all the polarities of the circuit elements.

The Attempt at a Solution

Completely blank. Simple. We havn't been told just how to deal woth current sources separately. Just no idea about these kind of problems.

Hope to learn it here.

Main problem was that we were confused that now there are two current sources. One the real current source and second the battery. What will be the effect now?

 

[CEL]

The labeling of the nodes is arbitrary. You put the plus sign wherever you want. The same is true for the direction of currents.
The associated labeling is when you attribute the direction of currents from the + to the - end of a branch. This convention is reversed when the branch contains a power source. In this case the current flows from - to +. So, the tail of the current source should be labeled -.

 

[piercas]

it is important to have a clear understanding of the concepts and principles being taught in a lab, especially when it comes to programming and circuit design. In this case, it seems that the students were not properly prepared for the mini-viva question and were unable to answer it confidently.

It is important for teachers to provide thorough explanations and examples when introducing new concepts, and to ensure that students have a solid understanding before moving on to more complex tasks. In this case, it may be beneficial for the teacher to review the concept of current sources and their polarities before the next class.

As for the question itself, the answer will depend on the specific circuit and how the current sources are connected. It is important to carefully label the nodes and understand the direction of the current flow in order to determine the polarity of the current sources. It may also be helpful to refer to Ohm's law and Kirchhoff's laws to guide the analysis of the circuit.

In conclusion, it is important for students to have a strong foundation in basic concepts before attempting more complex tasks, and for teachers to provide clear and thorough explanations to aid in understanding. With proper preparation and understanding, students will be better equipped to answer questions and solve problems confidently.