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(a) State the principle of an a.c. generator and explain its working with the help of a labelled diagram. Obtain the expression for the emf induced in a coil having N turns each of cross-sectional area A, rotating with a constant angular speed 'omega' in a magnetic field vecB, directed perpendicular to the axis of rotation. (b) An aeroplane is flying horizontally from west to east with a velocity of 900 km/hour. Calculate the potential difference developed between the ends of its wings having a span of 20 m. The horizontal component ofEarth's magnetic field is 5 xx 10^(-4)T and the angle of dip is 30^(@). |
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Answer» Solution :(a) See Long Answer Question Number 1. (b) Here velocity of aeroplane `V = 900 km h^(-1) = 900 5/18 m s^(-1)` due east, span of wing l = 20 m, horizontal COMPONENT of earth.s MAGNETIC field `B_(H) = 5 xx 10^(-4)T` and angle of dip `delta = 30^(@)` As plane is flying horizontally, an induced voltage is set up between the ENDS of its wings due to the vertical component of earth.s magnetic field. `therefore` Potential difference `V = vlB_(v) = vl B_(H) tan delta = 250 xx 20 xx 5 10^(-4) tan 30^(@) = 1.44 V` |
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