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www.GOALias.blogspot.comPhysicsFIGURE 6.2 Current isinduced in coil C 1due to motionof the current carrying coil C 2.moved towards the coil C 1, the galvanometer shows adeflection. This indicates that electric current is induced incoil C 1. When C 2is moved away, the galvanometer shows adeflection again, but this time in the opposite direction. Thedeflection lasts as long as coil C 2is in motion. When the coilC 2is held fixed and C 1is moved, the same effects are observed.Again, it is the relative motion between the coils that inducesthe electric current.Experiment 6.3The above two experiments involved relative motion betweena magnet and a coil and between two coils, respectively.Through another experiment, Faraday showed that thisrelative motion is not an absolute requirement. Figure 6.3shows two coils C 1and C 2held stationary. Coil C 1is connectedto galvanometer G while the second coil C 2is connected to abattery through a tapping key K.Interactive animation on Faraday’s experiments and Lenz’s law:http://micro.magnet.fsu.edu/electromagnet/java/faraday/index.htmlFIGURE 6.3 Experimental set-up for Experiment 6.3.It is observed that the galvanometer shows a momentary deflectionwhen the tapping key K is pressed. The pointer in the galvanometer returnsto zero immediately. If the key is held pressed continuously, there is nodeflection in the galvanometer. When the key is released, a momentorydeflection is observed again, but in the opposite direction. It is also observedthat the deflection increases dramatically when an iron rod is insertedinto the coils along their axis.2066.3 MAGNETIC FLUXFaraday’s great insight lay in discovering a simple mathematical relationto explain the series of experiments he carried out on electromagneticinduction. However, before we state and appreciate his laws, we must getfamiliar with the notion of magnetic flux, Φ B. Magnetic flux is defined inthe same way as electric flux is defined in Chapter 1. Magnetic flux through