Calculo de campos elétricos: Magnitudes individuais e ponto de campo nulo, Exercícios de Química

Baixe Calculo de campos elétricos: Magnitudes individuais e ponto de campo nulo e outras Exercícios em PDF para Química, somente na Docsity! 10. The individual magnitudes ∣∣∣
E1 ∣∣∣ and ∣∣∣
E2 ∣∣∣ are figured from Eq. 23-3, where the absolute value signs for q2 are unnecessary since this charge is positive. Whether we add the magnitudes or subtract them depends on if
E1 is in the same, or opposite, direction as
E2 . At points left of q1 (on the −x axis) the fields point in opposite directions, but there is no possibility of cancellation (zero net field) since ∣∣∣
E1 ∣∣∣ is everywhere bigger than ∣∣∣
E2 ∣∣∣ in this region. In the region between the charges (0 < x < d) both fields point leftward and there is no possibility of cancellation. At points to the right of q2 (where x > d),
E1 points leftward and
E2 points rightward so the net field in this range is
Enet = ∣∣∣
E2 ∣∣∣ − ∣∣∣
E1 ∣∣∣ in the î direction. Although |q1| > q2 there is the possibility of
Enet = 0 since these points are closer to q2 than to q1 . Thus, we look for the zero net field point in the x > d region: ∣∣∣
E1 ∣∣∣ = ∣∣∣
E2 ∣∣∣ 1 4πε0 |q1| x2 = 1 4πε0 q2 (x − d)2 which leads to x − d x = √ q2 |q1| = √ 2 5 . Thus, we obtain x = d 1− √ 2/5 ≈ 2.7d. A sketch of the field lines is shown below. • • .... ................. ....... ..... . ........ .............. . ........ .............. . ........ ...... .. ............... ......... .... . ........ ......... ..... . ..... ... .... ........... ........ .................. .. ........ .................... ........ ... ...... ..... ..... ..... .... . ........................... ........................................................... .................... ......... ......... ...... .... .... .... ... ...... ...... ............ ....................................... ........................... ............ ............................................. .................... ............. .......... ..... .............. ............................................................................... ................ ....................................................................................................................... ............................................................... ....... ...... ..... ..... ..... ..... ..... ..... ..... ..... .... .... .... ..... .. ............................................. ................................................................................................... .... .... .... .... .... .... .... .... .... .... .... . .... ..... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... ..... ..... .... .... .... ............................................................................. ............ ............. .............. ................ ...................... ................................................................................................................................................................... ................ ................ ................ ............ ......... .... .... ..... ..... ...... ..... ..... ..... ..... .... ... .... ..... ..... ..... ..... ..... ..... ..... ....