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(a) Find the magnitude and direction of the electric field at x = -1 m, y = 0 .

ID: 2124642 • Letter: #

Question

(a) Find the magnitude and direction of the electric field at x = -1 m, y = 0.

___ N/C

___ degrees (counterclockwise from plus x axis)

(b) Calculate the magnitude and direction of the force on an electron at x = -1 m, y = 0 .

___ N

___ degrees counterclockwise from plus x axis

A point charge of -7 mu C is located at x = 2 m, y = -2 m. A second point charge of 12 mu C is located at x = 1 m, y = 3 m. Find the magnitude and direction of the electric field at x = -1 m, y = 0. Calculate the magnitude and direction of the force on an electron at x = -1 m, y = 0 .

Explanation / Answer

a.Let charge q1: 4i - 2j -3 uC
Let charge q2: i + 2j 12 uC

Let point P: -i + 0j

The field at a point due to a point charge Q is:E = KQ r cap /r^2 that's the vector form of it:

The field due to charge q1 is:E1 = Kq1/-1-4)^2 + 0+2)^2 = -5i+2j/sqrt(29)

The field due to q2 is:-9535i -9535 jN/C

Add the fields together to get the total field:

The magnitude is given by:E = 7690 N/C

At an angle of:theta = 282.14 deg 0r -77.86 deg from +x axis.

The force on a point charge is: F = Eq

The electron has a charge of: -1.60*10^-19

The magnitude of the force it experiences is:

F =|E||q| = 1.23*10^-15 N

At angle which is 180 degrees from the field due to the negative charge of the electron, i.e.

? = 49 degrees

c. Because the electron has a negative charge, the angle will be rotated by 180 degrees.

You could add or subtract 180, but since you want the angle to be between:

0 and 360, or -180 and 180, you should just subtract 180.

282.140 - 180 = 102.14 degrees.