# Need help with physics! A man is standing beneath two rain clouds, equidistant from each cloud...?

A man is standing beneath two rain clouds, equidistant from each cloud, as shown in the figure. Cloud A has an excess of 6.6*10^4 negative charges while cloud B has 6.6* 10^4 positive charges (where a charge has magnitude e).

Cloud A and B are 0.5 km apart and 2 km above the man (I don’t know how to insert the diagram, sorry!)

WHAT IS THE MAGNITUDE OF THE NET ELECTRIC FIELD WHERE THE MAN IS STANDING?

Relevance

Have you tried using the formulas?

When a point charge Q is at a distance x horizontally and y vertically from a point, then r^2 = x^2 + y^2

so the field has magnitude E = kQ / r^2

But to get the horizontal and vertical components of field, we have to use similar triangles

In horizontal direction, E_x = E * x/r

= k*Q*x / r^3

Because of symmetry, vertical components of field will cancel out and the horizontal ones will add up.

Total E = 2E_x

= 2k*Q*x / r^3

= 2k*(6.6×10^4 e) * (250 m) / (250^2 + 2000^2 m^2)^(3/2)

= 5.8×10^-12 N/C

Source(s): Clouds that close are hardly points
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