Create Random password in C#.net

char[] a = { 'A', 'B', 'C', 'D', 'E', 'F','0','1','2','3','4','5','6','7','8','9', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z','0','1','2','3','4','5','6','7','8','9' };
char[] b = new char[10];
string s="";
Random rand = new Random();
for (int i = 0; i < 10; i++)
{
int randnum = rand.Next(0, 46);
b[i] = a[randnum];
s = s + b[i];
}
return s;