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Cork Institute of Technology
Higher Certificate in Engineering in Electronic Engineering
Stage 1
NFQ – Level 6
Autumn 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) Calculate the weight of a car of mass 1000 kg. (2 marks)
(b) Give one application of a convex mirror. (2 marks)
(c) Define acceleration. (2 marks)
(d) State the Laws of Reflection. (2 marks)
(e) Define Latent Heat of Fusion (lf ). (2 marks)
(f) Write 0.456 in Scientific notation. (2 marks)
(g) Name two modes of heat transfer. (2 marks) (h) Calculate the critical angle (of incidence) for glass with a refractive index of 1.
(2 marks)
(i) Calculate the wavelength of a radio wave transmission at a frequency of 96.4 Mhz. (2 marks) (j) An isotope of an element consists of atoms with different numbers of neutrons but the same number of protons. True/False?
(2 marks)
(k) A 50 kg pallet is lifted 6 m in 8 seconds. Calculate the output power of the lifting engine. (4 marks) (l) A braking force of –2000 N is applied to a small car of mass
700 kg moving at 40 ms -1^. Calculate the stopping time (4 marks)
(m) Name two metal alloys often used in Thermocouples and give the typical range of the sensor. (4 marks) (n) What type of radioactive decay is represented below?
21482 Pb → 214 83 Bi +− 01 e (4 marks)
(o) Calculate the energy needed to melt 1.2 kg of ice into water at 0 ºC (4 marks)
Question 5:
(a) Write a note on one engineering application of Ultrasonic sound waves. (5 marks) (b) Draw a sketch of the acoustic spectrum showing the frequency range of hearing for an average human ear and also the Ultrasonic region. Why is the decibel scale used for measuring sound levels? (7 marks) (c) A technician checking noise levels in a factory assembly area obtains a reading of 75 dB compared to 45 dB in the nearby office space. (i) What is the increase in loudness in decibels? (ii) How many times higher is the noise power in the assembly area compared to the office? (8 marks)
Question 6:
(a) What information about an element is given by the mass number (A) and atomic
number (Z)? 23 He has how many i) protons, ii) neutrons and iii) electrons? (6 marks) (b) Light of wavelength 720 nm is incident on a caesium surface in a photocell that has a Work Function of 1.475 eV. Calculate (i) the photon energy (6 marks) (ii) the maximum kinetic energy of the emitted electrons (8 marks)
______ o o o O O O o o o _______
