Recent content by steph124355

I have gotten this far: Using cos(2θ) = 1-tan2θ / 1+tan2θ From a previous question: Let θ= arctan(x): cos(2θ) = 1-tan2(arctan(x)) / 1+tan2(arctan(x)) =1-x2 / 1+x2 Where x2 cannot equal 0 or a negative number Have I done this in the right way and if so is this as far as I can...

haha thanks! physics does my head in but i enjoy it! thanks for your help

Use Gauss' law as though the cylinder is not there? In which case to calculate using E= λ/(2πε_0 r) and use the 2.5mm as the radial distance? Is there any different concepts behind this scenario compared to using a gaussian surface?

I'm a little stuck on the theory behind this question: (in relation to a line of infinite charge: a wire) A hollow cylindrical metal tube with inner radius 2.5mm is now placed around the wire, to form a coaxil cable. What will be the charge per unit length on the inner surface of the tube...