Which statement is true about vectors? a. All quantities in physics are not vectors. b. A vector may have either magnitude or direction. c. The vector's length should be proportional to its magnitude. d. Two vectors can be added only if they have the same direction.

Suppose a diode consists of a cylindrical cathode with a radius of 6.200×10^−2 cm , mounted coaxially within a cylindrical anode with a radius of 0.5580 cm . the potential difference between the anode and cathode is 260 v . an electron leaves the surface of the cathode with zero initial speed (v initial=0). find its speed vfinal when it strikes the anode.