magnetism. the greeks discovered a mineral that had a peculiar property it attracted metals, they...
TRANSCRIPT
![Page 1: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/1.jpg)
Magnetism
![Page 2: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/2.jpg)
Magnetism• The Greeks discovered a mineral that had a peculiar property
• It attracted metals, they found it in a place called Magnesia so they called it magnetic!
• Magnetism – refers to properties and interactions of magnets• Can be made of iron, cobalt, or nickel
![Page 3: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/3.jpg)
Magnetic Force• Not only do magnets attract metal objects, they also exert a force on each other
• Magnetic force – the attraction or repulsion felt between magnets
![Page 4: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/4.jpg)
Magnetic Field• A magnet is surrounded by a magnetic field which exerts the magnetic force
• Objects made of iron or another magnet are within the field it will react• The field can be shown with lines of
force or magnetic field lines
![Page 5: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/5.jpg)
Magnetic Poles• Magnetic Pole – area of a magnet where the magnetic force exerted is the strongest• North and South poles• North pole will point “North” like
a compass• Field lines always connect from
north pole to south pole
![Page 6: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/6.jpg)
Magnetic Poles
![Page 7: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/7.jpg)
Magnetic Poles
![Page 8: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/8.jpg)
Earth’s Magnetic Poles• Earth’s magnetic poles are opposite of what you would think!
• The N end of a compass needle points north…which means…
•The north pole of Earth is the south pole of Earth’s magnet!
![Page 9: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/9.jpg)
Magnetic Domain• Magnetic Domain – groups of atoms aligned with magnetic poles• In a magnet, all magnetic domains are aligned
![Page 10: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/10.jpg)
Isolated poles?!• Can we break a magnet in two?
• Sure we can! But what happens to the poles?
• There will still be a north and south pole!
![Page 11: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/11.jpg)
Electricity and Magnetism• Sometimes it helps to be lucky…• In 1820 a Danish physics teacher was demonstrating electric circuits• He had left a compass nearby the circuit and noticed as electricity was
flowing, the compass was deflected• He hypothesized that an electric current must produce a magnetic field
![Page 12: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/12.jpg)
Right Hand Rule• Moving charges flowing through a wire create a magnetic field
• The field forms a circular pattern around the wire• Direction of field depends on the current• The strength of the field depends on the strength of the current
![Page 13: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/13.jpg)
Right Hand Rule• The right hand rule helps determine the direction of the magnetic field• Current = I•Magnetic field = B
![Page 14: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/14.jpg)
Electromagnets• Electromagnet – a temporary magnet made by placing a piece of iron inside a current-carrying coil of wire• Temporary because they only
work while current is flowing
![Page 15: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/15.jpg)
Magnets Make Music• Speakers work because of electromagnets!• Information is read from a CD• That information varies electrical
current through a coiled wire• The electromagnet that is created is
attracted or repelled by a fixed magnet within the speaker• The causes vibration which creates
sound!
![Page 16: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/16.jpg)
Galvanometer• Galvanometer – a device that uses an electromagnet to measure electric current• Often used for gauges in a car• The greater the current the stronger
the electromagnet• The needle will push against a spring
to align with the poles of a permanent magnet
![Page 17: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/17.jpg)
Electric Motors• Electric motor – device that converts electrical energy into mechanical energy◦ Electric motor contains an
electromagnet that can rotate freely inside a permanent magnet
◦ When current flows the electromagnet produces a magnetic field
![Page 18: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/18.jpg)
Electric Motors• By flipping the flow of the current the poles of the electromagnet are switched and the coil can continue to rotate
•In some motors a communicator flips the flow of the current
• The greater the electric current the faster it will spin
![Page 19: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/19.jpg)
Question…• So we’ve seen that using an electric current and a magnet we can create a running motor
• What if we turned the current off and turned the wire coils ourselves?
![Page 20: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/20.jpg)
Electromagnetic Induction• Electromagnetic induction – producing an electric current by moving a loop of wire through a magnetic field
![Page 21: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/21.jpg)
Generator• Generator – produces electric current by rotating a coil of wire in a magnetic field
![Page 22: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/22.jpg)
Switching Direction• As the coil turns inside of a fixed magnet, the current will switch direction• This results in AC electric current!
![Page 23: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/23.jpg)
Power Plants• In order to generate power for you home and for cities power companies use massive generators
•Turbine – a large wheel pushed by water, wind, or steam
![Page 24: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/24.jpg)
Direct vs. Alternating Current• Two forms of electric current• Direct current (DC) – flows only in one direction in a wire• Batteries• Alternating Current (AC) – flows in 2 directions and alternates direction
in a regular way• Outlets in your home• 60 Hz in N. America
![Page 25: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/25.jpg)
Transformers• No…not Optimus Prime
• Transformer – a device that increases or decreases voltage of an alternating current
![Page 26: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/26.jpg)
Transformers
![Page 27: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/27.jpg)
Transformers• Step-up transformer• Secondary coil has more turns• This increases the voltage• Ex. Primary coil is 60V if the
secondary has 2 times the turns the secondary voltage will be 120V• 60V x 2 = 120V
• Step-down transformer• Secondary coil has fewer turns• This decreases the voltage• Ex. Primary coil is 120V and
secondary has half as many turns the secondary voltage will be 60V• 120V x ½ = 60V
![Page 28: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/28.jpg)
![Page 29: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/29.jpg)
Alternate Forms of Energy Hydroelectricity – creating electricity from moving water
![Page 30: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/30.jpg)
Alternate Forms of Energy Solar Energy – using the sun’s energy to create electricity
![Page 31: Magnetism. The Greeks discovered a mineral that had a peculiar property It attracted metals, they found it in a place called Magnesia so they called it](https://reader038.vdocuments.us/reader038/viewer/2022110208/56649ddc5503460f94ad43b1/html5/thumbnails/31.jpg)
Alternate Forms of Energy Wind Energy – Using wind turbines to produce energy