Summary
Summary OCR-A A2 Level Magnetic Fields Notes
A summary of magnetic fields, corresponding to Chapter 22 of the OCR Physics A textbook
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
Seller
Follow
Content preview
Magnetic FieldsMagnetic field patterns
● A magnetic field is a field surrounding a permanent magnet or a
current-carrying conductor in which magnetic objects experience
a force
○ You can detect the presence of a magnetic field with a small
plotting compass
○ The needle will deflect in the presence of a magnetic field
● Magnetic field lines map magnetic field patterns around magnetics
and current-carrying conductors
○ Magnetic field patterns are visual representations that help
us to interpret the direction and strength of the magnetic
fields
○ The arrow on a magnetic field points from north to south
○ Equally spaced and parallel magnetic field lines represent a
uniform field, so the strength of the field does not vary
○ The magnetic field is stronger when the magnetic field lines are closer
○ Like poles repel and unlike poles attract
Electromagnetism
● When a wire carries a current, a
magnetic field is created around the
wire
○ The field is created by the
electrons moving within the
wire
● Any charged particle that moves
creates a magnetic field in the space
around it
● For a current-carrying wire, the
magnetic field lines are concentric
circles centered on the wire and
perpendicular to it
○ The direction of the magnetic field can be determined using the
right-hand screw rule
● Both the coil and the solenoid produce north and south poles at their opposite
faces (Fig.5)
○ At the center of the core of the solenoid, it is uniform
, Magnetic fields and forces
● Magnets are made of alloys of a rare earth element, neodymium
● The strength of magnets, and magnetic fields, is measured in
Tesla
● A current-carrying conductor is surrounded by its own
magnetic field
○ When the conductor is placed in an external magnetic
field, the 2 fields interact like the fields of 2 permanent
magnets
○ The 2 magnets experience equal and opposite forces
● The direction of the force experienced by a current-carrying
conductor placed perpendicular to the external magnetic field
can be determined using Fleming’s left-hand rule
○ First finger gives the direction of the external magnetic
field
○ Second finger gives the direction of the conventional
current
○ Thumb gives the direction of motion (force) of the wire
Magnetic flux density
● The magnitude of the force experienced by a
wire in an external magnetic field depends on a
number of factors
○ The force is a maximum when the wire is
perpendicular to the field
○ The force is 0 when the wire is parallel to
the magnetic field
● The magnitude of the force experienced by the
wire is directly proportional to the:
○ Current
○ Length of the wire in the magnetic field
○ sin 𝛉, where 𝛉 is the angle between the
magnetic field and the current direction
○ The strength of the magnetic field
○ Therefore, F = BILsin𝛉
● B is the magnetic flux density - the strength of
the field - and is a vector quantity
○ The SI unit is the Tesla
● The magnetic flux density is 1T when a wire
carrying a current of 1A placed perpendicular to
the magnetic field experiences a force of 1N per meter of its length
● When the wire is perpendicular to the magnetic field, 𝛉 = 90° and sin 𝛉 = 1
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller annawoodbridge. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £4.49. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
73216 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy revision notes and other study material for 14 years now