Using the experimental apparatus shown in right figure, when a UV light with wavelength 1 = 240nm shines on a particular metal plate, electrons are emitted from plate 1, crossing the gap to plate 2 and causing a current to flow through the wire connecting two plates. The battery voltage is gradually increased until the current in the ammeter drops to zero, at which point the battery voltage is 1.40 V. Ask: a) What is the energy of the photons in the beam of light in eV? b) What is the maximum kinetic energy of the emitted electrons in eV? plate 2 LAV A Tammeter incident light plate 1 Pelectrons

Using the experimental apparatus shown in right figure, when a UV light with wavelength 1 = 240nm shines on a particular metal plate, electrons are emitted from plate 1, crossing the gap to plate 2 and causing a current to flow through the wire connecting two plates. The battery voltage is gradually increased until the current in the ammeter drops to zero, at which point the battery voltage is 1.40 V. Ask: a) What is the energy of the photons in the beam of light in eV? b) What is the maximum kinetic energy of the emitted electrons in eV? plate 2 LAV A Tammeter incident light plate 1 Pelectrons