Thermometric Property - Physics - Old Exam Paper, Exams of Physics

Download Thermometric Property - Physics - Old Exam Paper and more Exams Physics in PDF only on Docsity! Cork Institute of Technology Bachelor of Engineering (Honours) in Structural Engineering – Stage 1 (NFQ – Level 8) Summer 2007 Physics (Time: 3 Hours) Answer FIVE questions only. Show ALL working to gain full marks. Assume: g = 10.0 ms-2 Examiners: Prof. P. O Donoghue Mr. P. Anthony Dr. M. E. Woods Q1. (a) (i) What is a thermometric property of a thermometer? (ii) State the thermometric property of ONE named thermometer. (4 marks) (b) The tungsten filament of a lamp has a length of 0.6 m and a radius of 20 µm. The power rating of the lamp is 50 W. Assume that the wire emits radiation equivalent to 80 % of that of a black body radiator at the same temperature. (i) What is a black body? State its emissivity (ε) value. (3 marks) (ii) Estimate the temperature of the filament. Assume that absorption of radiation from the surroundings is negligible. (9 marks) [Stefan’s Constant σ = 5.7 x 10-8 Wm-2 K-4] (c) A cavity wall of a house with an air gap emits 3.0 kW of heat through it walls which have an area of 90 m2 when the internal temperature of the house is 28oC and the external temperature is 3 oC. Determine the U-value of the wall. [4 marks] Q2 (a) (i) Sketch a fully-labelled ray diagram of a refracting astronomical telescope operating in normal adjustment incorporating two converging lenses of focal length fo and fe [fo > fe]. Indicate all relevant distances, angles and images. [6 marks] (ii) State the location, orientation and nature of the final image. [3 marks] (iii) State the magnification equation for the telescope. [1 mark] (iv) What additional device is incorporated into a terrestrial telescope? How does this device affect the final image? [2 marks] (b) An object is placed 50 cm from a thin converging lens (lens1) and produces a real image at a distance of 75 cm from the lens. A second thin lens (lens 2) is then placed in contact with the first lens and the focal length of the combination is measured to be fc = + 80 cm (i) Calculate the individual focal lengths of the two lenses. [5 marks] (ii) State with a reason whether the second lens is diverging or converging. [1 mark] (iii) Calculate the magnification of lens1. [2 marks] Q3 (a) Define the following categories of wave and name ONE physical property, which belongs to that type: (i) longitudinal wave (ii) transverse wave. [5 marks] (b) A boat traveling along a river generates a progressive wave, whose displacement y is given by: ))xft(2sin(Ay λ+π= The water wave has a frequency of 0.3 Hz, an amplitude of 7.5 cm and a wavelength of 80 cm. (i) Sketch a labelled diagram of displacement (y) versus position (x) for the condition t = 0 s. Indicate the wavelength and amplitude on the plot. [4 marks] (ii) State the wave equation and hence determine the wave velocity (units: ms-1). [4 marks] (iii) Determine the period (T) of the wave. [2 marks] (iv) State the equation for the particle velocity and determine its value (units: ms-1) for x = 0 cm, t = 5.0 s. [5 marks]