Direction of Compass Needle near a Solenoid

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Homework Help Overview

The discussion revolves around the behavior of a compass needle when placed near a solenoid, particularly focusing on the direction it points in relation to the magnetic fields involved. The subject area includes electromagnetism and magnetic fields.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the interaction between the solenoid's magnetic field and the Earth's magnetic field, questioning how these fields influence the compass needle's direction. Some express confusion about the implications of equal field strengths and the resulting compass behavior.

Discussion Status

The discussion is active, with participants sharing their thoughts and clarifying concepts related to magnetic fields. Some guidance has been provided regarding the nature of magnetic fields as vectors, and there is an ongoing exploration of the correct answer based on the given conditions.

Contextual Notes

Participants are grappling with the implications of the solenoid's magnetic field strength being equal to that of the Earth's magnetic field, which introduces complexity in determining the compass needle's direction. There is also mention of a textbook answer that may not align with some participants' reasoning.

aadarsh9
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A compass is placed near a solenoid. It is closer to the North pole generated by the coil. The magnetic north is 90 deg relative to the compass and the solenoid. The strength of the solenoid is equal to the strength of the magnetic north. In which direction will the compass needle point?
 
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hi aadarsh9! welcome to pf! :wink:

tell us what you think, and why (with full explanation), and then we'll comment! :smile:
 
Since the current is from X to Y, a north pole will be induced near the compass. I would say that the compass needle will point towards the solenoid but it says that the field strength is equal to that of Earth's magnetic field. I can only eliminate answer D. Then, I am lost. The answer is A according to the book.
 
One component to the right and another one upwards. Is the answer C?
 
aadarsh9 said:
One component to the right and another one upwards. Is the answer C?

i'm confused:

C is to the left and upwards …

which one do you mean? :confused:​
 
Sorry, its one component to the left and another one upwards. Is it C?
 
Th book says A :(
 
What you need to know is that th Earth's magnet has its S pole at the North pole. Thus, the needle of a compass has its N side pointing North (approximately).

Use that fact and I think you'll see why the answer is indeed A (compass needle points NE).
 
  • #10
(just got up :zzz:)
rude man said:
What you need to know is that th Earth's magnet has its S pole at the North pole.

yes! :biggrin:

aadarsh9, do you understand why that is so?
 
  • #11
Thanks tiny-tim and rude man. I understood it!
 

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