Light source Light P Photocell (A V FIGURE 27-6 The photoelectric effect.

(b) According to Bohr's atomic model, a one-electron system is described by the atomic number Z and the speed vn of the electron at a radius m in the n-th quantum orbit: Z.e² 1 h² €0 Vn = 2.h.Eon rn •N² π ● me e². Z me (i) Calculate the radius and the velocity for the first quantum orbit of the single ionised helium atom. (ii) Calculate the value for the velocity uncertainty, Avx, of the electron in the singly ionised helium atom results, if a spatial uncertainty Ax of the electron is assumed to be the diameter of the first quantum orbit. (iii) Explain the relationship between simultaneous measurements of Bohr's orbit radius and the orbit speed on the first quantum orbit. ●

II) What is the maximum kinetic energy of electronsejected from barium(Wo = 2.48eV) when illuminated bywhite light,λ =400 to 750 nm?

When 250-nm light falls on a metal, the current through aphotoelectric circuit (Fig.27–6) is brought to zero at a stoppingvoltage of 1.64 V. What is the work function of the metal?