A constant electric field of magnitude E = 148 V/m points in the positive x-direction. How much work (in J) does it take to move the charge Q =-13 μC from x1 = -81 m, y1 = -131 m, to x2 = 107 m, y2 = 76 m? (Please note: the charge is given in micro-Coulomb. The symbol in front of the C should be a Greek letter mu.)

Respuesta :

Answer:

[tex]W=-2.1405\times 10^9\,J[/tex]

Explanation:

Given:

electric field, [tex]E=148\,V.m^{-1}[/tex]

charge, [tex]Q=-13\,\mu C=-13\times 10^{-6}\,C[/tex]

initial position coordinates, [tex]p1 =(-18,-131)[/tex]

final position coordinates,   [tex]p2 =(107,76)[/tex]

We find the distance through which the charge has been moved:

[tex]d=\sqrt{(x1-x2)^2+(y1-y2)^2}[/tex]

Where we have (x1,y1) & (x2,y2) as the initial and final coordinates of the points.

[tex]d=\sqrt{(107-(-81))^2+(76-(-131))^2}[/tex]

[tex]d= 279.63\,m[/tex]

Now we need the angle through which displacement is made with respect to the direction of electric field.

[tex]tan\,\theta= \frac{y2-y1}{x2-x1}[/tex]

[tex]\theta= tan^{-1}[\frac{76-(-131)}{107-(-81)} ][/tex]

[tex]\theta= 47.75^{\circ}[/tex]

Now from the relation between the change in potential difference:

[tex]\Delta V= E.d.cos\,\theta[/tex]

[tex]\Delta V= 148\times 279.63\times cos\,47.75^{\circ}[/tex]

[tex]\Delta V= 27826.06 V [/tex]

∵The change in voltage is defined as the work done per unit charge.

∴[tex]\Delta V=\frac{W}{Q}[/tex]

[tex]W=\frac{\Delta V}{Q}[/tex]

Putting the respective values

[tex]W=\frac{27826.06 }{-13\times 10^{-6}}[/tex]

[tex]W=-2.1405\times 10^9\,J[/tex]