lenz law -general physics
Name: Grade & Section: Score: School: Teacher: Subject: General Physics 2 LAS Writer: JAN JEFFREY R. CAMINA Content Editor: Learning Topic: Lenz's Law; Quarter 4-Week 1 LAS 1 Learning Targets: Describe the direction of the Induced electric field, magnetic field, and current on a conductingonconducting loop using Lenz's Law. STEM_GP12EM-IVA-5 Reference(s): Wolfe, Gregg, Erika Gasper, John Stoke, Julie Kretchman, David Anderson, Nathan Czuba, Liza Pujji, Irina Lyublinskaya, and Douglas Ingram. 2015. "Faraday'S Law Of Induction: Lenz'S Law". Openstax. https://openstax.org/books/college-physics-ap-courses/pages/23-2-faradays-law-of- induction-lenzs-law. Lenz's Law Faraday's experiments shows that the induced emf e by a change in magnetic Faraday's Law of depends on a few factors: Induction: 1. emf e is directly proportional to the change in flux 4; e = -N- do 2. emf e is greatest when the change in time At is smallest; 3. If a coil has / turns, emf e is proportional to the number of turns N. This relationship is known as Faraday's Law of Induction. The unit for emf e is volts V. (a) The minus sign means that "emf e creates a current / and magnetic field B that oppose the change in flux 4". This S N statement is known as Lenz's Law. The directions of the opposing magnetic field B and current I is shown in Figure 1. (b) Example: S If a coil conductor is connected to a 3 kQ resistor, what would N be the rated voltage and current that would be measured if the north pole of the magnet is moving closer to the coil conductor and the rate of change of flux is 3 wb/s and the (c) number of turns is three? Given: AN - ON N = 3 turns 3.0 k Figure 1. (a) When this bar magnet is thrusted into the de = 3 wb/s de coil, the strength of the magnetic field B increases in the R = 3 kQ = 3 x 103 0 coil. The current induced in the coil creates another field, S in the opposite / direction of the bar magnets to oppose the increase. This is one aspect of Lenz's law-induction Solution: opposes any change in flux. (b) and (c) are two other situations. Verify for yourself that the direction of the e = N- = (3) 310 =9V induced Bcoil shown indeed opposes the change in flux 4 and that the current direction shown is consistent with By following Fig. 1 (a) it can the right-hand rule in Attachment A.1. 3.0 kQ be seen that the motion of the magnet makes the induced current move clockwise, therefore making S the measured voltage positive. By Ohm's Law where V = e: Conclusion: 9V Therefore, the rated voltage across the resistor is 9 V and I= R R= 3 x 103 0 = 3 x 10-3 A or 3 mA the rated current passing through the resistor is 3 mA. Activity: Solve for the rated current and rated voltage, on the given figure, when the V number of turns of the conductor is eight (8) and the rate of change is 4 wb/s on the given situations; (a) the south pole of the magnet is moving 5.0 KQ towards the coil conductor and (b) the south pole of the magnet is moving away from the coil conductor. Write your answers on a separate sheet of paper and illustrate the direction of the current. Use the rubrics as your N guide in presenting your solution (refer to attachment A.2 at the next page). A.1 Right Hand Rule (Ampere's Law) Where; I = Current B = Magnetic field
