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An object that attracts iron containing objects Has two poles North and south Law of poles- Like poles repel while opposite attract.

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Presentation on theme: "An object that attracts iron containing objects Has two poles North and south Law of poles- Like poles repel while opposite attract."— Presentation transcript:

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2 An object that attracts iron containing objects Has two poles North and south Law of poles- Like poles repel while opposite attract

3 A bar magnet is divided into two pieces. Which of the following statements is true? A) the bar magnet is demagnetized B) the magnetic field of each separated piece becomes stronger C)the magnetic poles are separated D) two new bar magnets are created

4 A region in which the magnetic force can be detected The magnetic fields go from the north pole to the south pole

5 Magnetic Field Diagram # 3

6 Also called flux lines Never cross each other The closer they are the stronger the field

7 ???

8 The north pole is actually the south pole of Earth’s magnet! The magnetic south pole is near the geographic North pole and vice versa. This is why compasses point to the south pole of a magnet in a magnetic field but we say that compasses point north

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10 Which of the following statements is most correct? A. The north pole of a freely rotating magnet points north because the magnetic pole near the geographic North Pole is like the north pole of a magnet. B. The north pole of a freely rotating magnet points north because the magnetic pole near the geographic North Pole is like the south pole of a magnet. C. The north pole of a freely rotating magnet points south because the magnetic pole near the geographic South Pole is like the north pole of a magnet. D. The north pole of a freely rotating magnet points south because the magnetic pole near the geographic South Pole is like the south pole of a magnet.

11 Caused by moving charges Any time a charge moves (current) a magnetic field is created So….electric current can create magnetic fields Magnetic force is created by two magnetic fields occupying the same space

12 Electrons have a spin, so there are moving charges in atoms Most atoms’ electrons are paired up though and spinning in opposite directions, so the fields that are generated are cancelled When the electrons are not paired up then the fields are not cancelled These materials can be magnetic

13 Electric Fields Caused from a positive or negative charges Charges can be moving or stationary Fields move from positive to negative Can be caused by a single charge Magnetic Fields Caused from moving charges Field lines move from north to south pole Always caused from two poles

14 When there is an electric current a magnetic field (B-field) is created around it Use the right hand rule Thumb will point in the direction of the current Fingers will curl in the direction of the B field

15 An electric current flows into the page. What is the direction of the magnetic field? A) to the bottom of the page B)to the top of the page C)Clockwise D)counter-clockwise E) to the right

16 A current is flowing to the right, in what direction will the magnetic field be? A)Into the page B)out of the page C)clockwise D)counter-clockwise E)to the left

17 Solenoid is a long helically wound coil of wire Solenoids produce a strong magnetic field by combining several loops More loops= stronger magnetic field

18 A charge moving through a magnetic field experiences a magnetic force The force is proportional to the Charge Velocity Magnetic field

19 Alternative Right Hand Rule Direction of your palm=magnetic force Fingers= magnetic field lines Thumb=velocity of particle When drawing An X= into the page A  = out of the page

20 A positive charge enters a uniform magnetic field as shown. What is the direction of the magnetic force? Velocity is pointed up and fields pointed into page. A) out of the page B) into the page C) downwards D) to the right E) to the left

21 A positive charge enters a uniform magnetic field. What is the direction of the magnetic force? The velocity is to the right and the magnetic field is into the page. A) out of the page B) into the page C) Downwards D) upwards E) to the left

22 If two wires were parallel to each other and the current was in the same direction, they would attract If the current is in the opposite direction they would repel

23 Changing magnetic fields creates a potential difference (or EMF) in a conductor So.. Magnetic fields can create currents This allows physical work to create electrical energy

24 Power that is generated for transmission (for homes and buildings) is ramped up (about V) when it arrives at your home you need it at a lower level (120V) To convert voltage to a higher or lower value we use a transformer

25 Consists of a primary coil and a secondary coil The current flows through the primary  magnetic field Magnetic field  current in secondary coil We use alternating current for this When a transformer increases voltage it is called a step up (more secondary coils) When a transformer decrease voltage it is called a step down (more primary coils)


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