*18 The circuit diagram shows three identical resistors an…

*18 The circuit diagram shows three identical resistors and two switches, X and Y. The battery has negligible internal resistance.   See addendum Figure 18.1   Each resistor consists of a wire of diameter 0.181 mm and length 55.0 cm. At room temperature, the resistivity of the wire is 1.10 × 10−6 Ω m.   (a) Show that the resistance of one resistor at room temperature is about 24 Ω. (3)       (b) A student suggests that the maximum power output from the resistors in this circuit will be greater than 12 W. Assess whether the student’s suggestion is correct. (4)       (c) Switch X was open and switch Y was closed.   (i) Calculate the number of conduction electrons passing through the resistor every second immediately after switch Y was closed. (3) (ii) After switch Y had been closed for a few minutes, the power dissipated by the resistor decreased. Explain why. (3)   (Total for question 18 = 13 marks)

4 The diagram shows some of the energy levels of a hydroge…

4 The diagram shows some of the energy levels of a hydrogen atom.   See addendum Figure 4.1 An excited electron in the level –0.54 eV drops to the level –13.60 eV, resulting in the release of at least one photon.   Which of the following photon energy values could not be produced from this electron transition? (1)

4 The diagram shows some of the energy levels of a hydroge…

4 The diagram shows some of the energy levels of a hydrogen atom.   See addendum Figure 4.1 An excited electron in the level –0.54 eV drops to the level –13.60 eV, resulting in the release of at least one photon.   Which of the following photon energy values could not be produced from this electron transition? (1)

13 A student used two sources, A and B, of electromagnetic…

13 A student used two sources, A and B, of electromagnetic radiation to investigate the photoelectric effect. Radiation from A has a photon energy of 2.0 eV.   (a) The radiation from B has a wavelength of 280 nm. Show that this radiation has a photon energy of about 4.4 eV. (4)       *(b) The student used the two sources of radiation to investigate the photoelectric effect for two different metals, copper and zinc.   The following statements were made by the student.   See addendum  Paragraph 13.1   Explain the conclusions that can be made from these statements. (6)   (Total for question 13 = 10 marks)