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## Homework Statement

I am confused about two parts of the question. 1 How are they getting the calculation of dB/dt=0.06 and how do they know the direction of the field is perpendicular to r and couterclockwise?

A magnetic field directed into the page changes with time according to B=(0.03t^2+1.4)T, where t is in seconds. The field has a circular cross section of radius R=2.5cm. What are the magnitude and direction of the electric field at point P1 when t=3.00s and r1=0.02m.

The figure is located on this webpage at the bottom: http://www.phys.ncyu.edu.tw/~ccliu/index.files/course2.files/Ch29to31Appl.pdf [Broken]

It's basically a circle. P2 is on the outside going toward the center. P1 is going up and to the right but is inside the circle. R in going down and right out of the circle.

## Homework Equations

I am confused about two parts of the question. 1 How are they getting the calculation of dB/dt=0.06 and how do they know the direction of the field is perpendicular to r and couterclockwise?

## The Attempt at a Solution

dB/dt=0.06t

E=(0.02m/2)(0.06)(3)(1) =1.8*10^-3 directed perpendicular to r1 and counterclockwise.

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