Resolução - Halliday - Volume 3 - Eletricidade E Magnetismo - P23 009

Transcript

9. At points between the charges, the individual electric fields are in the same direction and do not cancel. Charge q2 has a greater magnitude than charge q1 , so a point of zero field must be closer to q1 than to q2 . It must be to the right of q1 on the diagram. • q2 d • q1 P • We put the origin at q2 and let x be the coordinate of P , the point where the field vanishes. Then, the total electric field at P is given by
 q2 q1 1 − E= 4πε0 x2 (x − d)2 where q1 and q2 are the magnitudes of the charges. If the field is to vanish, q2 q1 = . x2 (x − d)2 √ √ We take the square root of both sides to obtain q2 /x = q1 /(x − d). The solution for x is
 √ q2 x = d √ √ q2 − q1 
√ 4.0q1 √ d = √ 4.0q1 − q1 
2.0 d = 2.0d = 2.0 − 1.0 = (2.0)(50 cm) = 100 cm . The point is 50 cm to the right of q1 .