# Magnetic field due to a solenoid

• Jahnavi
In summary: When the solenoid is cut, the length becomes 1/4th of the original and number of turns also become 1/4th of the original. This interpretation gives option 4) . Right ?Can you explain this .You didn't use the part about quarters to arrive at the answer of B/2, right?Option 2) is the answer given .Please see the solution.

## The Attempt at a Solution

I am having trouble interpreting the language of the problem statement . What does it mean that "half number of turns are wound " ?

When the solenoid is cut , the length becomes 1/4th of the original and number of turns also become 1/4th of the original .

I think the problem is not difficult if only I could understand the question .

Thanks .

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• solenoid.png
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Merlin3189
That is a strange question. Are the four equal parts picked up again later?
If not, I don't understand that part. I would assume the density of the windings (windings per length) is halved.

Jahnavi
mfb said:
Are the four equal parts picked up again later?

I think so .

mfb said:
I would assume the density of the windings (windings per length) is halved.

How ?

What does it mean "half number of turns wound on anyone piece " ?

Last edited:
Well, the sentence does not use correct English grammar, so it is a bit speculation, but I interpreted it as "For each quarter, we halve the winding density". For the following question this means the quarters don't matter.
Jahnavi said:
I think so .
Can you show the full problem with its context?

mfb said:
Can you show the full problem with its context?

That is all I have . This is an objective type MCQ from a test paper .

mfb said:
I interpreted it as "For each quarter, we halve the winding density".

This interpretation gives option 4) . Right ?

mfb said:
For the following question this means the quarters don't matter.

Could you explain this .

Jahnavi said:
This interpretation gives option 4) . Right ?
Sure.
Jahnavi said:
Could you explain this .
You didn't use the part about quarters to arrive at the answer of B/2, right?

Jahnavi

I think what they ( paper setters ) are trying to do is halving the total number of turns (before the solenoid is cut ) and then fitting those N/2 turns in the length L/4 ( after the solenoid is cut in four ) . Strange interpretation .

Please let me know if the official solution makes sense to you .

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• Solution3.png
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I can see how you could interpret the problem that way, but the phrasing is unnecessarily complicated and ambiguous.

Jahnavi
Thanks !

## What is a solenoid?

A solenoid is a coil of wire that is tightly wound in a helical shape. It is often used to create a magnetic field when an electric current is passed through it.

## How is a magnetic field created by a solenoid?

When an electric current flows through a solenoid, it creates a magnetic field. The direction of the magnetic field can be determined by the right-hand rule, where the fingers of your right hand curl in the direction of the current and your thumb points in the direction of the magnetic field.

## What factors affect the strength of the magnetic field created by a solenoid?

The strength of the magnetic field created by a solenoid is affected by the number of turns in the coil, the amount of current flowing through the coil, and the permeability of the material inside the coil.

## How does the direction of the magnetic field change inside a solenoid?

Inside a solenoid, the magnetic field is uniform and parallel to the axis of the coil. This means that the direction of the magnetic field remains the same at all points inside the solenoid.

## What are some real-world applications of solenoids?

Solenoids are commonly used in devices such as electromagnets, speakers, and electric motors. They are also used in industrial equipment, medical devices, and security systems.