Two concentric metal spherical shells, of radius a and b, respectively, are separated by weakly conducting material of conductivity ơ (see part (a) of figure). (a) (b) a. If they are m aintained at a potenti al difference V, what current flows from one to the other? b. What is the resistan ce between the shells? c. Notice that if b > a the outer radius bis irrelevant. How do you account for that? Exploit this observation to determine the current flowing between two metal spheres, each of radius a, immer sed deep in the sea and held quite far apart (see part (b) of figure), if the potential difference between them is V. (This arr angement can be used to measure the conductivity of sea water.)

Two concentric metal spherical shells, of radius a and b, respectively, are separated by weakly conducting material of conductivity ơ (see part (a) of figure). (a) (b) a. If they are m aintained at a potenti al difference V, what current flows from one to the other? b. What is the resistan ce between the shells? c. Notice that if b > a the outer radius bis irrelevant. How do you account for that? Exploit this observation to determine the current flowing between two metal spheres, each of radius a, immer sed deep in the sea and held quite far apart (see part (b) of figure), if the potential difference between them is V. (This arr angement can be used to measure the conductivity of sea water.)