Question 1:

Protons in an accelerator are moving at 3 x 10" and produce a beam current of 4 MA. If the radius of the beam id 2 mm, find: a) the current density: A b) the density of particles: particlesWhen 140 V is applied across a wire of length 20 m and radius 1.8 mm, a current of 15 A flows through it. Find the resistivity of the material.The resistances of a copper wire and an aluminium wire are equal. What is the ratio of the lengths low/Al if they have the same diameter? The resistivity of copper is 1.7 x 10 0 . m and the resistivity of Aluminium is 2.8 x 10 0 . m