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Cork Institute of Technology
Higher Certificate in Engineering in Electronic Engineering - Stage 1
(National Certificate in Engineering in Electronic Engineering – Stage 1)
(NFQ – Level 6)
Summer 2005
Engineering Physics
(Time: 3 Hours)
Examiners: Mr. D. Polley Mr. J. Berry Dr. R. O’Dubhghaill
Instructions to Candidates
You are required to answer question 1 , along with any three questions of your choice from the remaining five questions.
Question 1 carries 40%. All other questions carry 20%.
Table of Constants
1 eV = 1.6x 10 -19^ J Charge on an electron, e = 1.6 x 10-19^ C Planck's Constant, h = 6.64 x 10-34^ J s Acceleration due to gravity, g = 9.81 m s- Speed of light in a vacuum, c = 3 x 10^8 m s - Threshold of hearing, 0 dB = 1 x 10-12^ Wm - Specific heat capacity of water = 4.2 kJ kg-1^ K - Specific heat capacity of ice = 2.1 kJ kg-1^ K - Latent heat of fusion of ice = 335 kJ kg- Latent heat of vaporisation of water = 2.26 MJ kg-
Linear expansion coefficient of Steel = 1.2 x 10-5^ K -
Question 1: (Attempt all parts)
(a) Give the SI units for length and temperature. (2 marks)
(b) A vector is a quantity which has magnitude but no direction. ( True/False )?
(2 marks)
(c) Define acceleration. (2 marks)
(d) Write 0.276 mA in Scientific notation format. (2 marks)
(e) What is the weight of a a car of 1800 kg mass? (2 marks)
(f) With a transverse wave, displacement occurs in a direction parallel to the direction of propagation. ( True/False )?
(2 marks)
(g) Name two modes of heat transfer. (2 marks)
(h) State the Conservation of Momentum Principle. (2 marks) (i) Cork 96FM is transmitted at a frequency of 96.4 Mhz. Calculate the wavelength of this radio wave. (2 marks) (j) In relation to radioactive decay, what is meant by the term Half-life of a element? (2 marks) (k) A force of 150 N moves a block 2 m along a smooth horizontal surface. The force is applied at an angle of 15o^ to the horizontal. Calculate the work done.
(4 marks)
(l) A braking force of –2000 N is applied to a small car of mass
700 kg moving at 30 ms -1^. Calculate the stopping time. (4 marks)
(m) (^) A 1000 kg cannon fires a 20 kg shell horizontally at 150 ms-^.
Calculate the recoil velocity of the cannon.. (4 marks) (n) (^) An experiment to measure the refractive index , η of a glass
block sample yields the following data; Real depth = 64 mm, Apparent depth = 40 mm. Calculate η.
(4 marks)
(o) A particular diffraction grating has 600 lines per mm etched onto its surface. What is the inter-line spacing, d? (4 marks)
(a) Write a note on one engineering application of Ultrasonic sound waves. (5 marks) (b) Define the term intensity of a sound wave. Give one reason why the decibel scale is used for measuring sound levels. (4 marks) (c) A Health & Safety technician checks the noise levels near a vacuum unit in a canning plant. A reading of 85 dB is recorded. Repairs and adjustments are made to the unit and the new reading obtained is 60 dB at the same distance. (i) Express each reading as an Intensity level. (6 marks) (ii) Calculate the ratio of the two noise intensities and express it as a dB value. (3 marks) (iii) Calculate the noise reduction directly from the original dB values. Does your answer compare with part (ii)? (2 marks)
Question 6:
(a) Write brief descriptions of Alpha, and Beta and Gamma radiations, making reference to their nature, ionising ability and penetration power. (9 marks) (b) Explain briefly what the Photoelectric Equation means. (5 marks) (c) Light of wavelength 450 nm is incident on a photoelectric surface whose work function, W = 3.5 x 10-19^ J. Determine the kinetic energy of the emitted electrons (6 marks)
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