It gets weaker, because that's a principle of electromagnets. The field force is directly proportional with tension.
The equation for range is:
R = v₀²sin(2θ)/g
To find the maximum R, differentiate the equation and equate to zero. The solution is as follows:
dR/dθ = (v₀²/g)(sin 2θ)
dR/dθ = (v₀²/g)(cos 2θ)(2) = 0
cos 2θ = 0
2θ = cos⁻¹ 0 = 90
θ = 90/2
<em>θ = 45°</em>
Need a picture of the problem
