{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

zhang20

# zhang20 - First exam Saturday 12-2pm Covers Ch15-Ch18...

This preview shows pages 1–5. Sign up to view the full content.

2/14/2010 1 First exam: 02/22/09, Saturday; 12-2pm Covers: Ch15-Ch18 Format: 12 MC (3 MC/chapter): 12x3 = 36 points 4 problems (one per chapter): 4x16 = 64 points Formula sheet: One letter size, both sides Room assignment: Check for announcement Makeup exam: Check for announcement Students with disabilities: Please contact your office for exam scheduling. Induced Voltages and Inductance How does electric generator work?

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2/14/2010 2 A carton box A strong bar magnet A small flashlight light bulb A long thin conducting wire (with insulating layer) One of the greatest scientists in history Invented electric motor, generator and transformers Discovered electromagnetic induction Discovered laws of electrolysis 1791 1867
2/14/2010 3 A current can be produced by a changing magnetic field (more precisely, changing magnetic flux ) First shown in an experiment by Michael Faraday A primary coil is connected to a battery A secondary coil is connected to an ammeter First observation: An electrical current is produced by a changing magnetic field Careful analysis: The emf is actually induced by a change in the quantity called the magnetic flux rather than simply by a change in the magnetic field How can you tell it is the changing field or flux that matters? What is magnetic flux?

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
4 A current loop in a uniform magnetic field The loop has an area A The magnetic flux is defined as where θ is the angle between B and the normal direction of the plane Normal <-> perpendicular B ) cos( BA A B B When the field is perpendicular to the plane of the loop (a) θ = 0, Φ B = Φ B, max = BA When the field is parallel to the plane of the loop (b) θ = 90° , Φ B = 0 SI units of flux are T . m² = Wb (Weber)
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 15

zhang20 - First exam Saturday 12-2pm Covers Ch15-Ch18...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online