A small 12.4 g plastic ball is tired to a very light 28.1 cm string that is atta

Question

A small 12.4 g plastic ball is tired to a very light 28.1 cm string that is attached to the vertical wall of a room

Problem 21.65 A small 12.4 g plastic ball is tied to a very light 28.1 cm string that is attached to the vertical wall of a room. (See the figure (Figure 1) A uniform horizontal electric field exists in this room. When the ball has been given an excess charge of -1.50 AuC you observe that it remains suspended, with the string making an angle of 17.4 with the wall. of 1 Figure 1 17.4 Part A Find the magnitude of the electric field in the room AE N/C Submit My Answers Give Up Part B Find the direction of the electric field in the room O to the right O to the left Submit My Answers Give U Provide Feedback Continue

Explanation / Answer

Using force balance:

In y-direction:

T*cos A = mg

in x-direction

T*sin A = qE

dividing both equations::

tan A = qE/mg

E = m*g*tan A/q

using the given values:

E = 12.4*10^-3*9.81*tan 17.4 deg/(1.5*10^-6)

E = 25413.95 N/C

Since it's a negative charge direction of electric field will be to the left.

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