An electron confined to a one-dimensional box has a ground-state energy of 13.8 eV. If the electron makes a transition from its first excited state to the ground state, what is the wavelength of the emitted photon

An air-filled capacitor is formed from two long conducting cylindrical shells that are coaxial and have radii of 26 mm and 103 mm. the electric potential of the inner conductor with respect to the outer conductor is - 700 v (k = 1/4πε 0 = 8.99 × 109 n · m2/c2) the energy stored in a 1.0-m length of this capacitor is closest to