A battery of e.m.f 3.0V is connected across a potentiometer wire AB of length 10(Omega m^{-1}) as illustrated in the diagram above. If the jockey J makes contact at the 30cm mark, determine the resistance of length AJ and voltage across AJ.
-
A.
3.0(Omega); 0.9V -
B.
3.0(Omega); 3.0V -
C.
3.3(Omega); 0.3V -
D.
3.3(Omega); 9.0V
Correct Answer: Option A
Explanation
E = 3.0V; (frac{R}{l} = 10Omega m^{-1})
l = 30cm = 0.3m; R = (10Omega m^{-1} times 0.3m = 3Omega)
(frac{E}{V} = frac{l_{1}}{l_{2}} implies frac{3}{V} = frac{1}{0.3})
= (frac{3times 0.3}{1} = 0.9V)