Calculating e.m.f Induced By Cycling Handlebars

[sara_87]

Homework Statement

An eager student cycles to college at 12 m/s. The metal handle bars are 60 cm wide and cut through the vertical component of the Earth’s magnetic field that has a flux density of 50 *10^(-6) T. Calculate the e.m.f induced across the handlebars. Explain why no current would flow through the student when he touched the metal parts of the handlebars even if he were a good electrical conductor.

The Attempt at a Solution

i can find the e.m.f:

e.m.f= -3.6 * 10^(-4)

but i can't explain why ...i think it has something to do with F=BIL


any help would be much appreciated

 

[Dick]

It is indeed because there is no changing flux through the loop of student+handlebars. But you can also ask yourself what e.m.f. is induced across the hands of the student.

 

[sara_87]

the emf that i calculated in the first part of the question?

 

[Dick]

Yes, the student has the same e.m.f. as the handlebars. Does any current flow?

 

[sara_87]

i don't get it, i don't see how any of this is linked

 

[Dick]

If you have two batteries with equal voltage and you connect their positive terminals together and the negative terminals together, how much current flows in the loop? It's the same problem.

 

[sara_87]

is it zero current?

 

[Dick]

Yes. There's no e.m.f. difference between the two positive terminals or the two negative terminals. Do you see why your problem is the same?

 

[sara_87]

it's because the student and the handle bars have the same e.m.f...?

 

[Dick]

Yes again.

 

[sara_87]

Oh thanks a lot i get it all now