slide 23-39
DESCRIPTION
Additional Clicker Questions. In the circuit shown below, the switch is initially closed and the bulb glows brightly. When the switch is opened, what happens to the brightness of the bulb? The brightness of the bulb is not affected. B.The bulb gets dimmer. C.The bulb gets brighter. - PowerPoint PPT PresentationTRANSCRIPT
2. In the circuit shown below, the switch is initially closed and the bulb glows brightly. When the switch is opened, what happens to the brightness of the bulb?
A. The brightness of the bulb is not affected.B. The bulb gets dimmer.C. The bulb gets brighter.D. The bulb initially brightens, then dims.E. The bulb initially dims, then brightens.
Slide 23-39
Additional Clicker Questions
2. In the circuit shown below, the switch is initially closed and the bulb glows brightly. When the switch is opened, what happens to the brightness of the bulb?
B. The bulb gets dimmer.
Slide 23-40
Answer
Capacitor Concepts
Slide 24-2
Key Equations for Circuits – another way to look at loop rule
Slide 24-2
• Magnets and the magnetic field
• Electric currents create magnetic fields
• Magnetic fields of wires, loops, and solenoids
• Magnetic forces on charges and currents
• Magnets and magnetic materials
Chapter 24Magnetic Fields and Forces
Topics:
Sample question:This image of a patient’s knee was made with magnetic fields, not x rays. How can we use magnetic fields to visualize the inside of the body?
Slide 24-1
3-D Arrows, Cross Products, and Right Hand Rule 1
Slide 24-2
• Showing vectors in 3D
• Cross Product
For direction use Right-hand rule 1
• Right-hand rule 1 (RHR 1) => for finding direction of cross-product vector
(Cross-Product Rule)1.Point right hand in the direction of the first vector (vector A)
2.Rotate your right hand until you can point your fingers in the direction of the second vector (vector B)
3.Thumb points in direction the cross-product vector (vector C)
Electric vs. Magnetic Interactions
1. Nature of Magnetic Interactions
Slide 24-2
Discovering Magnetism
Slide 24-6
The Magnetic Field
Slide 24-7
Mapping Out the Field of a Bar Magnet
Slide 24-8
Mapping Out the Magnetic Field Using Iron Filings
Slide 24-9
Drawing Field Lines of a Bar Magnet
Slide 24-10
Magnetic Fields Produced by Bar Magnets
A single bar magnet A single bar magnet(closeup)
Slide 24-11
Magnetic Fields Produced by Bar Magnets
Two bar magnets, unlike poles facing
Two bar magnets,like poles facing
Slide 24-12
Checking Understanding
Slide 24-13
Magnetic Fields from Two MagnetsBar Magnets A and B are placed at right angles. Two compasses, X and Y are placed so that they are equidistant from the two magnets as shown
A.) The arrow in compass X indicates the direction in which the North pole of the compass is pointing. Indicate the North and South ends of both magnets in the diagram
B.) Draw an arrow in compass Y to show the direction in which the North pole of the compass needle would point.
Slide 24-2
Magnetic Fields Around Us
Slide 24-14
Key Points• Three types of magnetic interactions
1. no interaction with either pole of a magnet => object is non-magnetic
2. attracted to both poles of a magnet => object is magnetic
3. Attracted to one pole and repelled by the other pole=> object is a magnet
• Magnetic field vector from a bar magnet is a super position of the magnetic field vectors from the N and S poles:
• Vector from N pole points away from N pole
• Vector from S pole points towards S pole
• Field lines form complete loops inside and outside of magnet• Field lines outside magnet go from N to S poles
• Field lines inside magnet go from S to N poles
• Magnetic Field vectors at a point are tangential to Magnetic Field Lines
Electric Currents Also Create Magnetic Fields
A long, straight wire
A current loop A solenoid
Slide 24-15
The Magnetic Field of a Straight Current-Carrying Wire
Slide 24-16
Slide 24-17
Representing Vectors and Currents That Are Perpendicular to the Page
Slide 24-18
Checking Understanding
Point P is 5 cm above the wire as you look straight down at it. In which direction is the magnetic field at P?
Slide 24-19
Answer
Point P is 5 cm above the wire as you look straight down at it. In which direction is the magnetic field at P?
Slide 24-20
Drawing Field Vectors and Field Lines of a Current-Carrying Wire
Slide 24-21
Drawing a Current Loop
Slide 24-22
The Magnetic Field of a Current Loop
Slide 24-23
The Magnetic Field of a Solenoid
A short solenoid A long solenoid
Slide 24-24
The Magnitude of the Field due to a Long, Straight, Current-Carrying Wire
Slide 24-25
Slide 24-26
Checking Understanding
A. 10 A to the right.
B. 5 A to the right.
C. 2.5 A to the right.
D. 10 A to the left.
E. 5 A to the left.
F. 2.5 A to the left.
The magnetic field at point P is zero. What are the magnitude and direction of the current in the lower wire?
Slide 24-27
E. 5 A to the left.
The magnetic field at point P is zero. What are the magnitude and direction of the current in the lower wire?
Slide 24-28
Answer