As per given figure A, B and C are the first, second and third excited energy level of hydrogen atom respectively. If the ratio of the two wavelengths (ie. \(\frac{λ_1}{λ_2}\)) is \(\frac{7}{4n}\) , then the value of n will be____.
A network of four resistances is connected to 9V battery, as shown in figure. The magnitude of voltage difference between the points A and B is ______V.