Chapter 20 Induced Voltages and Inductance 1 Induce
- Slides: 28
Chapter 20 Induced Voltages and Inductance 1. Induce emf and Magnetic flux 2. Faraday’s law of induction 3. Lenz’s law 4. Motional emf 5. Generators 6. Self-Inductance 7. RL circuits 8. Energy stored in a magnetic field
Michael Faraday n n n 1791 – 1867 Great experimental scientist Invented electric motor, generator and transformers Discovered electromagnetic induction Discovered laws of electrolysis
Faraday’s Experiment – Set Up n n What is induced emf? How is it produced?
Magnetic Flux n n n What is magnetic flux? How do I calculate it? What is the SI units? Why the angle dependence? Flux and B
Electromagnetic Induction – An Experiment n n What is electromagnetic induction? What is induced current?
Example 1. The quarter-circle loop shown in figure has an area of 15 cm 2. A magnetic field, with B=0. 16 T exists in the +x direction. Find the flux through the loop in each orientation shown.
Example a) B n plane normal 20º B B 20º 70º normal b) plane c) 20º
Faraday’s Law and Electromagnetic Induction n n What is Faraday’s law? What is the formula? What is the SI units? How to change the flux? What is Lenz’s law?
Example 1. As shown a metal rod makes contact with a partial circuit. The circuit is perpendicular to the magnetic field. Find the induced emf if the rod moves with velocity of v=2 m/s. Assume L=0. 5 m
Lenz’ Law – Example
Example 1. See figures
Example 1. See figures
Applications of Faraday’s Law – Ground Fault Interrupters
Applications of Faraday’s Law – Apnea Monitor
Application of Faraday’s Law – Motional emf n n What is motional emf? How is it produced? n n The force on charges The potential difference
Motional emf in a Circuit n n n How do I calculate motional emf? Motional emf and Battery What is the resulting current?
Example 1. As shown, a metal rod makes contact with a partial circuit and completes the circuit. The circuit area is perpendicular to the magnetic field with B=0. 15 T. If the resistance of the total circuit is 3 ohm, how large a force is needed to move the rod as indicated with a speed of 2 m/s.
Lenz’ Law Revisited – Moving Bar Example n n How do I calculate the direction of induced current? One possibility
Lenz’ Law, Bar Example n n Another possibility Conservation of energy
Lenz’ Law – Moving Magnet Example n When applying Lenz’ Law, there are two magnetic fields to consider n n The external changing magnetic field that induces the current in the loop The magnetic field produced by the current in the loop
AC Generators n n n What is a generator? How does it work? Emf of the loop
DC Generators
Motors n n What is a Motor? Motors an Back
Joseph Henry n n n 1797 – 1878 First director of the Smithsonian First president of the Academy of Natural Science First to produce an electric current with a magnetic field Improved the design of the electro-magnetic and constructed a motor Discovered self-inductance
Self-inductance n n n What is self-inductance? How do I calculate it? What are it SI units? What is inductance? How do I calculate it?
Example 1. A coiled telephone cord has 70 turns, a crosssectional diameter of 1. 3 cm, and an unstrectched length of 60 cm. Determine an approximate value for the self-inductance of the unstretched cord.
Inductor and RL Circuit n n n What is an inductor? How does it work in a circuit? RL circuit What is the time constant? How do I find the current in the circuit? What is the energy stored in the inductor?
Example For the circuit shown, determine 1. 1. 2. 3. 4. Time constant Current after one time constant Change in potential at t=0 and t=first time constant The rate of change of current after first time constant
- Induced dipole
- Deduce and induce
- Charging by induction
- Generation of high dc voltage
- Electrical tools and their uses
- Koshland induced fit theory
- Inductance and capacitance formula
- Magnetic flux and inductance
- Inductors in dc circuits
- Capacitor and inductor
- Relationship between capacitance and inductance
- Induced fit vs lock and key
- Magnetism and electromagnetism gcse
- Induced fit model vs lock and key
- Magnetizing inductance
- Self inductance
- Self-inductance of a solenoid
- Emf formula inductance
- Magnetizing inductance
- Inductance matrix
- Imflux course
- Electronics circuit 2
- What is interpoles in dc machine
- Hay bridge circuit
- Inductance units
- L
- Finding equivalent inductance
- What is inductance in physics
- Tuned amplifier ppt