What are we doing Today? Ch. 5 Magnetism •Homework Questions Check •Hand in Lab 41-42 •Chapter 5 Notes •In class questions & homework
Dec 26, 2015
What are we doing Today?Ch. 5 Magnetism
• Homework Questions Check • Hand in Lab 41-42• Chapter 5 Notes• In class questions & homework
Magnetism (Chapter 5 - p.163)
Magnet – An object that can attract other objects containing iron, cobalt or nickel
Magnetic PolesThe The strengthstrength of a magnet is of a magnet is concentrated at the ends, concentrated at the ends, called north and south called north and south ““polespoles” of the magnet.” of the magnet.
NNSS
N
E
W
SNN
CompassCompassBar magnetBar magnet
S
N
Iron filings
Magnetism (Chapter 5 - p.163)
Magnetic Field – Is the area of space in which the magnetic force of a magnet can act on another magnet.
Magnetic Field Lines
N S
We can describe We can describe magnetic field linesmagnetic field lines by imagining a tiny by imagining a tiny compass placed at compass placed at nearby points.nearby points.
The The directiondirection of the of the magnetic field magnetic field BB at at any point is the same any point is the same as the direction as the direction indicated by this indicated by this compass. compass.
Field Lines Between Magnets
N S
N N
Unlike poles
Like poles
Leave N and enter S
Attraction
Repulsion
Ferromagnetic Substance (p.167)
Ferromagnetic materials are materials that have magnetic properties similar to those of iron. They can become permanently magnetized. Examples of ferromagnetic materials are nickel and cobalt.
ELECTROMAGNET
Electromagnetisma moving charge (electricity) produces a magnetic field
• More coils of wire= more current = stronger magnet
• Bigger battery = stronger magnet
A magnet with a field produced by an electric current
• Magnetic field pattern around a straight wire.
• The resulting magnetic field lines form concentric circles around the wire.
The Right-Hand rule can be used to predict the direction of the magnetic field
The Electromagnet
By the Right Hand Rule, a coil of wire with current flowing in it will create a magnetic field
The strength of the magnetic field depends onThe amount of current in a wire – More current
means stronger magnetic fieldThe number of turns in the coil – More turns
means stronger magnetic fieldThe material in the coil – Magnetic materials like
iron and steel make the magnetic field stronger
The Electromagnet• A simple electromagnet can be made by
coiling some wire around a steel nail, and connecting a battery to it.
• As current rotates around the nail, a magnetic field is created with the North pole at the bottom and the South pole at the top
The Electromagnet
• Electromagnets are found in many everyday objects such as– Motors and generators– Doorbells– Speakers– Hard drives– VHS and Audio cassette tapes– Telephones
Exit Question(s)Draw the following circuits and which of the circuits below are connected in series, and which are connected in parallel?
The circuit is composed of a 6.0-V battery connected to a 10-Ω resistor. It includes an ammeter and a voltmeter connected to the resistor terminals.(look up in chapter 5 on diagrams of circuits).
a) Draw the circuit diagram, including the measuring instruments.
Exit Questions1) The potential difference in a circuit is determined to be 10 volts. If the resistance is 5 ohms, what must the current intensity be?
The potential difference in a circuit is determined to be 10 volts. If the resistance is 5
ohms, what must the current intensity be? Answer:1. Determine what you are looking for.2. List what you know and don’t know.• V = 10 Volts• R = 5 ohms• I = ?3. Use equation V = R x I Solve for I, so I = V/R4. I = 10 Volts / 5 ohms = 2 AAnswer: The current intensity will be 2 A (Amps)