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UNIVERSITY EXAMINATIONS: 2008/2009 STAGE I EXAMINATION FOR DIPLOMA IN INFORMATION TECHNOLOGY DIT 102: FOUNDATION PHYSICS AND ELECTRICITY DATE: APRIL 2010 TIME: 1½HOURS INSTRUCTIONS: Answer any THREE questions Question One a) Define the following terms as used in optics (i) Reflection (ii) Diffraction (iii) Photon (iv) UV [4 Marks] b) One of the applications of photonics is in the field of communication. Explain the construction and operation of the optic-fiber in this regard. [6 Marks] c) State any three wave properties that make light a better transmission medium than sound. [3 Marks] d) An infra-red range finder works by sending an IR signal that is then reflected by the target to an IR detector. Calculate the distance if the sent signal is received in 60ns. [3 Marks] e) State Snell’s law and calculate the angle of refraction if the angle of incidence is 20o while the refractive indexes for the first and second media are 0.6 and 0.56 respectively. [4 Marks] Question Two a) Briefly explain the terms below i) Work ii) Energy 2 iii) Potential energy iv)Power [4 Marks] b) State the first two of Newtons laws [2 Marks] c) Using the first two of Newton’s laws of motion explain the following events i) A passenger wearing a safety belt is safer if a car comes to a sudden stop ii) A loaded truck has difficulty gaining speed when going up a hill (In each case state the relevant law and show the application) [4 Marks] d) A crane uses a 35000N force to pull a 3000Kg mass upwards. Calculate i) The time it takes to lift it through 32m ii) The velocity of the mass [6 Marks] e) Use a graph to show the displacement of an object that is shot vertically up from the ground. Explain the gradient of the curve [4 Marks] Question Three a) With regard to sound waves explain the following properties i) Speed ii) Frequency iii)Amplitude [6 Marks] b) Explain the difference between longitudinal and transverse waves [2 Marks] c) Discuss production of sound in open pipes [3 Marks] d) A closed pipe has a second harmonic of 1000Hz. Find the difference in length between it an open pipe whose fundamental frequency is 1000Hz. [5 Marks] e) Wave interference may result in standing waves. Explain this term and the conditions that cause them. [4 Marks] Question Four a) Name any two standards in use today [2 Marks] b) Explain the difference between weight and mass [2 Marks] c) A 200N force pulls a 40Kg mass up an incline. (i) If the static friction is 20N, find the angle of inclination below which the mass will sli (ii) Hence find the acceleration of the mass at an angle of 15o and 40o assuming a kinetic frictional force of 10N [10 Marks] 3 d) The force acting on a charge Q is given by F = kQQ’/r2 where Q’ is another charged placed a distance r away from the first. i. Give the units of measure of each of the four constituent terms in the formula [2 Marks] ii. Name the law and its significance [2 Marks] iii. Calculate the force acting between two electrons placed 12x10-12m apart [2 Marks] Question Five a) We have Electrical materials and Magnetic materials. For each give two types and explain the difference between them. [6 Marks] b) With regard to electricity define the terms i. Resistance ii. Current iii.Voltage [3 Marks] c) Show the mathematical relation between the terms in Q5b above [1 Mark] d) State faradays law as used in magnetism. [2 Marks] e) From the circuit below; calculate i) The current flow through the 5KO resistor ii) The current through the 1kO resistors iii) The voltage across the 2kO resistor iv)Total resistance [8 Marks] + Battery 8V R3 5k Fig.1