CBSE Class 12-science Physics Motional emf

•   Please refer to the uploaded image for the doubt
  
• why EMF is induced before current in the experiment dobe by Faraday?
• What happens when a toroid uses bismuth in its core?
• A jet plane is travelling due west at the speed of 1800 km/h. what is the voltage difference developed between the ends of the wings 25m long, if the earths magnetic field at the location is 0.0005 T and the dip angle is 30°?  
• What is induced emf ?
• The figure shows the variation of field strength versus time of a loop kept in a magnetic field From the graph answer the following questions: a) Would there be any induced voltage if yes state when? b) During BC, CD and DE will there be flow of current?
• What are the conditions under which no emf will be induced in the circuit?
• Calculate the emf induced in a wire of 2 m moving with a speed of 15 m/s perpendicular to a magnetic field of 2 Wb /m².
• Induced emf results into induced current, which laws help in finding the direction of this current?
• The expression for magnetic flux is given by Calculate the emf induced at t = 3 s.

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