Question

In an electromagnetic induction experiment, you are keeping a conducting circular loop of 50 cm radius placed perpendicular to a magnetic field of 5 T and magnetic field changed from maximum to zero within 0.50 s. Is law of electromagnetic induction applied here? Justify your answer. How can you evaluate the magnitude of induced emf in the coil? When the circular coil having a diameter of 20 cm is used in above case, evaluate the induced emf? Compare your results and select which provides more induced emf? If earth’s magnetic field is used here what will be the change? Justify your answer

Answer 1

As per law of electromagnetic induction Whenever a conductor is placed in a varying magnetic field, EMF induces and this emf is called an induced emf.

As there is change in magnetic field through the coil, flux will change and this will induce emf.

E = - Nd / dt

E = - Nd ( BA) / dt

E = - NA dB / dt

E = - 1 * * 0.5² * ( 0 - 5) / 0.50

E = 7.853 V

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Now, when diameter is 20 cm means radius is 10 cm

then

E = - 1 * * 0.1² * ( 0 - 5) / 0.50

E = 0.314 V

as we notice, the induce emf has reduced too much, this means lesser the area, lesser magnetic field lines can pass through it

Therefore,

more EMF is induced when radius was 50 cm

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If we use earth's magnetic field ( 50 uT) , then EMF will be reduced drastically