In a very large circular region, there is a uniform magnetic field pointing into

Question

In a very large circular region, there is a uniform magnetic field pointing into the page. An xy coordinate system has its origin at the circular region's center. A free positive point charge +Q = 1.0 microC is initially at rest at a position x = + 10 cm on the x axis.

If the magnitude of the magnetic field is now decreased at a rate of -0.24 T/s, what force (magnitude and direction) will act on +Q?

My first attempt was to use the equation E=(r/2)*(dB/dt) and find the electrostatic field first. After finding E I used the equation E=F/q and solved for F.

The solutions i got are E=-0.012 and F=-1.2*10^8.
But the system tells me that this is wrong, and i am out of options.
Can somebody help please?

Explanation / Answer

Your numbers look right. Maybe this is a sign or direction problem?

The flux is pointing in and decreasing. By Lenz's law, the induced E field is going to try to make charges move so as to oppose that change. Your positive charge that is on the x axis is going to want to move clockwise, in the negative y direction; that, by the right hand rule, will make its B field towards the center of the loop point in to the page, counteracting the other change.

So your Fx = 0 and Fy = -1.2 * 10-8. (and the E field is similarly oriented). Is that maybe the problem?

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.