7.2.1 Example 9

7.2.1 of Griffith's Introduction to Electrodynamics 2nd Ed
Here, quasistatics show that there is a need for corrections to our basic laws when the magnetic field is changing. However, the results are good enough within a certain small radius.
Next: • 7.2.2 Inductance
Previous: • 7.2.1 Example 8
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[@loghorg]

Hi I do not understand why E only points along the direction of the current

[@shaheedperez5692]

Bro this question was asked 9 years ago and I still have the same question 😢💀

[@user-wt3ev1zg2l]

@@shaheedperez5692 You can see from the formula that the induced electric field is created by the changing magnetic field. Since the magnetic field varies with distance from the wire, the electric field of the vertical sides of the loop will cancel since they are the same distance away but opposite directions. Only the horizontal remains. At least this is what I believe is happening.

[@shaheedperez5692]

Hey ​@user-wt3ev1zg2l thx for feedback I had to study it for a test last week so I understand it now

[@user-wt3ev1zg2l]

@@shaheedperez5692 ofc. And looking back on this, I think a nicer explanation is that we know that the magnetic field is pointing out of the page and the loop is moving up so by the RHR where your fingers represent the velocity, palm represents magnetic field and thus the electric field has to point along your thumb to the right. for anyone who has this question in the future.

[@user-wt3ev1zg2l]

or that this situation would create the same effect as the changing current.

[@ruchi9917]

How do we get the direction of induced electric field?! Should we use Biot Savarts law or Lenz law? :/

[@thephysicsmindset9614]

How did you find the value of B?

[@user-up4vh1eb1m]

We can find B by using ampere's law