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PH2111 ENGINEERING PHYSICS Question bank for first year engineering students PART I

Question bank

UNIT- I
(ultrasonics)

PART-A (2-Marks)                                                                                                                                                                                                                                                                                                                               

1. What are ultrasonics?
2. Name a few methods by which   ultrasonic waves are produced.
3. State the phenomenon of magnetostriction                                                                                                                                       
4 .Name the advantages, disadvantages of magnetostriction oscillator.
5. What is piezo electric effect?
6. What is inverse piezo electric effect?
7. List out the advantages of piezo electric oscillator
8. What are the applications of ultrasonics in industry?
9. Is it possible to produce ultrasonic waves, by passing high frequency alternating current thro a loud speaker? Justifies your answer.
10. What are the properties of ultrasonic waves?
11. What is pulse echo technique?
12. Give few applications of ultrasonics.
13. What is meant by cavitation?
14. What is sonar?
15. What is an acoustic grating?
16. Are ultrasonic waves electromagnetic waves? Justify your answer.
17.  Mention a few medical applications of ultrasonics waves.
18. What are the industrial applications of ultrasonic waves?

                                                         
                                                      Part-B (16-Marks)
1  . What is meant by of magnetostriction? Explain how ultrasonics are produced in an mgnetostriction oscillator.  

   2.  Explain the inverse piezo electric effect. Describe the piezo electric method of                                     producing ultrasonic waves.

3. With relevant theory explain how the velocity of ultrasonic waves in liquid can be determined by using an acoustic grating.
4. (a) Describe the different methods of detecting ultrasonic waves.

    (b) List out the properties of ultrasonic waves.

5.  Explain the process of non-destructive testing of materials using pulse echo technique.

6. Explain the different display modes of ultrasonic transmission system.

7. Explain how ultrasonic waves are useful in the following application
     (a) SONAR
     (b)  Non-destructive testing
                                                          PROBLEMS
1). For a quartz crystal of length 0.05m, calculate the fundamental frequency of oscillation in a piezo-electric oscillator if the velocity of longitudinal waves in the crystal is 5.5 x 103 m/s

2) For a iron rod of length 40 mm, calculate  the natural frequency if it’s density 7.25 x  103 Kg/m3 and Young’s modules is 115 x 10 9 N/m2

3) An ultrasonic source of 0.07 MHz sends down a pulse towards the seabed which returns after 0.65 sec. The velocity of sound in sea water is 1700 m/s. calculate the depth of sea and the wave length of pulse.

4)      Calculate the velocity of ultrasonic waves in a certain liquid using the following data obtained in an acoustic grating expt.
Frequency
 of ultrasonic wave = 100 MHz
Wavelength of light used = 600 nm
Angle of first order diffracted beam = 5

5)      A quartz crystal in an ultrasonic interferometer produces stationary waves of frequency 1.5 MHz. If the distance between 6 consecutive nodes is 2.75 mm, find the velocity of the ultrasonic waves.  
                                   

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