PHYS 1420 Exam # 2 Study Guide Lectures: 5, 7Lecture 1 (February 17)Chapter 21: Magnetic forces and Magnetic fields Equations and concepts 1) Fmagnetic- When a charge is placed in a magnetic field, that charge experiencesa magnetic force; when two conditions exist: 1) the charge is moving relative to the magnetic field, 2) the charge's velocity has a component perpendicular to the direction of themagnetic field2) Right hand rules-Recitation notes for chapter 21Lecture 2 (March 3) Chapter 22: electromagnetic inductionElectromagnetic induction is the phenomena in which an emf is induced in a piece of wire or a coil of wire with the aid of a magnetic field. The emf is called an induced emf, and any current that results from the emf is called an induced current. Motional emf- εmotion=vB×L, where L is the length of the object moving at speed v relative to the magnet.Magnetic flux- the magnetic flux is proportional to the number of magnetic field lines that pass through the surface. Faraday’s law of electromagnetic induction- The average emf induced in a coil of N loops given by equation, Lenz’s law- is a common way of understanding how electromagnetic circuits obey Newton's third law and the conservation of energy. The electric generator- consist of a coil of N loops that rotate in a uniform magnetic field. Covert mechanical energy to electric energy. ΦB = BA cos θ = BA cos ωt. Flux through one loop is ΦB = BA cos ωt Mutual inductance and self-inductance- deals with the effect in which a changing current in the primary coil induces an emf in the secondary coil. Es =-MΔIp/Δt E =-L ΔI/ ΔtEnergy= 1/2LI^2 Energy density=1/2μ0 B^2Transformers- consist of a primary coil of Np turns and a secondary coil of Ns turns. Vs/Vp = Ns/NpIs/Ip =