I have 4 - 7.5 W bulbs in parallel. E=120 v. If I open the neutral some bulbs go dim, and others go brighter. Circuit 1 is controlled by 2 SPDT switches, and Circuit 3 has a DPDT controlling a light from Circuit 1, and a receptacle with plugged in lights on Circuit 3. Why are they lighting if I open the neutral?
Open neutral calculation L1 to N
- Thread starter pstout44
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I approved this post because you appear to be studying electric circuits -BUT, before anyone here answers a homework or lab experiment - present your explanation first.
Potential does not flow, it drops for current to flow. Do as Hv&LV says, draw your two circuits (1 & 3 + N) out with all the combinations of switching you described and use ohms law to show why the loads dim and increase.
Roger
kwired
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Draw what you have, then erase the neutral connection, what is left. Remember for current to flow there has to be a closed circuit. By taking away the neutral you have modified the circuit but have not left the remaining components in an open circuit condition.
This same thing happens when a service or feeder or even a multiwire branch circuit, which is what you are describing, has a problem on the neutral and it becomes opened.
This same thing happens when a service or feeder or even a multiwire branch circuit, which is what you are describing, has a problem on the neutral and it becomes opened.
gar
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pstout44:
You do not have four bulbs in parallel. There is something not complete or inconsistent in the statement of your problem. Do you have the actual circuit for experimental use? The word neutral and the indication of a single voltage source is critical to why there is some confusion.
Start thinking in terms of ideal voltage and current sources. One way of drawing these is to draw a circle with either V or I in the center of the circle to identify whether it is a voltage or current source. Then two wires leave opposite sides of the circle.
Can you define the characteristics of an ideal voltage or current source?
For the moment consider only resistances as possible loads of the source. Resistors are commonly drawing as as a zig-zag line. Do you understand Ohm's law? Do you understand that the sum of the voltages around a closed loop is zero? And that the sum of the currents at a node (point) is zero?
As the others have suggested draw the circuit for your problem.
From what kind of course is this problem?
An old professor of mine would never answer a question that you asked him relative to a class problem. He would tell you to study the question, answer the best you could, and if you thought the question had a problem, then describe what was wrong with the question and how to correct the question.
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pstout44:
You do not have four bulbs in parallel. There is something not complete or inconsistent in the statement of your problem. Do you have the actual circuit for experimental use? The word neutral and the indication of a single voltage source is critical to why there is some confusion.
Start thinking in terms of ideal voltage and current sources. One way of drawing these is to draw a circle with either V or I in the center of the circle to identify whether it is a voltage or current source. Then two wires leave opposite sides of the circle.
Can you define the characteristics of an ideal voltage or current source?
For the moment consider only resistances as possible loads of the source. Resistors are commonly drawing as as a zig-zag line. Do you understand Ohm's law? Do you understand that the sum of the voltages around a closed loop is zero? And that the sum of the currents at a node (point) is zero?
As the others have suggested draw the circuit for your problem.
From what kind of course is this problem?
An old professor of mine would never answer a question that you asked him relative to a class problem. He would tell you to study the question, answer the best you could, and if you thought the question had a problem, then describe what was wrong with the question and how to correct the question.
.
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