A circular current with center O and radius R = 20 cm has a current of magnitude I1 = 10A flowing through it. a) Calculate the magnitude of the induction vector from B at center O.
b) An infinitely long straight current of magnitude I2 = 5A flows through center O and coincides with the axis
of the circular current I1. Calculate the magnitude of the magnetic induction vector B produced by two currents I1 and I2 at
point M lies on the straight current I2 and is a distance x = 20 cm from the center of O.

Uranium has two naturally occurring isotopes. 238u has a natural abundance of 99.3% and 235u has an abundance of 0.7%. it is the rarer 235u that is needed for nuclear reactors. the isotopes are separated by forming uranium hexafluoride uf6, which is a gas, then allowing it to diffuse through a series of porous membranes. 235uf6 has a slightly larger rms speed than 238uf6 and diffuses slightly faster. many repetitions of this procedure gradually separate the two isotopes. what is the ratio of the rms speed of 235uf6 to that of 238uf6? express your answer to five significant figures.