07a1bs03 Engineering Physics

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD I YEAR B.TECH. Ist MID TERM EXAMINATION ENGINEERING PHYSICS – 07A1BS03 UNIT-1 1.

Explain the principle of superposition of waves.

2.

Derive the conditions for the maxima and minima in the Young’s experiment. [5M] What is interference of light waves? What are the conditions necessary for obtaining interference fringes? [5M]

3.a) b) 4.a) b)

[5M]

Explain the terms: i. constructive interference and ii. destructive interference. When the Young’s experiment was done with blue light of 436 nm, the distance between two successive dark fringes was found to be 1.05 mm. If the distance between the sources and the screen is 1.40 m, calculate the distance between the two slits. [5M]

5.

Explain, with necessary theory, how the colours are formed when a little oil is spread on a wet road. [5M]

6

Derive an expression for the radius of the nth bright ring in the case of Newton’s rings. [5M]

7.

Prove that in the reflected light, the diameters of the dark Newton’s rings are proportional to the square roots of natural numbers. [5M]

8.

Describe the experimental procedure to find the radius of curvature of a planoconvex lens by forming Newton’s rings. [5M]

9.

In a Newton’s rings experiment, the diameters of the 6th and 12th dark rings are 0.42 cm and 0.69 cm respectively. Find the diameter of the 20th dark ring. [5M]

10

The diameter of the tenth bright ring in a Newton’s rings experiment changes from 1.40 cm to 1.27 cm when a liquid is introduced between the lens and plate. Find the refractive index of the liquid. [5M]

11.

What is diffraction? Distinguish between Fresnel and Fraunhofer iffractions.[5M]

12

Discuss, in detail, Fraunhofer diffraction at two slits.

[5M]

13

Explain, in detail, Fraunhofer diffraction due to single slit.

[5M]

14

Explain, in detail, the diffraction due to multiple slits.

[5M] Contd…2

::2:: 15

Describe the experimental procedure to find the wavelengths of spectral lines of mercury with the help of a transmission grating. [5M]

16.

A parallel beam of monochromatic light is incident normally on a plane diffraction grating having 6000 lines per cm. Calculate the angular separation between the two lines of wavelengths 589 nm and 592 nm in the second order. [5M]

17.

Write notes on: i) Diffraction grating and ii) Resolving power of a grating.

[5M]

Explain, in detail, Rayleigh’s criterion for resolving power.

[5M]

18

19.a) How resolving power of a telescope can be improved? b) Calculate the linear separation between two points at a distance of 10 km from a telescope objective of width 0.55 m if the wavelength of light used is 650 nm. [5M] 20. A grating has got 30000 lines. What is its resolving power for the first order spectrum? If the mean wavelength of two lines in this spectrum which can be just resolved is 600 nm, what is the difference of their wavelengths? [5M] 21

Distinguish between ‘interference’ and ‘diffraction’ of light.

[5M]

22

(a) Distinguish between polarized light and unpolarized light. (b) Write notes on ‘double refraction’.

[5M]

23

(a) What is Brewster’s law? Explain. (b) Find the Brewster angle for a glass slab (refractive index =1.50) immersed in water (refractive index = 4/3). [5M]

24

Describe various methods to produce plane polarized light.

25

Distinguish between o-ray and e-ray, and hence explain how a beam of circularly polarized light can be obtained. [5M]

26

Describe the phenomenon of interference of polarized light.

[5M]

27

Describe the construction of a Nicol prism.

[5M]

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[5M]

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD I YEAR B.TECH. Ist MIDE TERM EXAMINATION ENGINEERING PHYSICS - 07A1BS03

UNIT-II 1.

Explain: i) magnetostriction effect and ii) piezo-electric effect.

[5M]

2.

What are ultrasonic waves? Write their properties.

[5M]

3.

Describe the methods employed for detection of ultrasonic waves.

[5M]

4.

Describe the production of ultrasonics by magnetostriction method.

[5M]

5.

Describe the production of ultrasonics by piezo-electric method.

[5M]

6.

What is non-destructive testing of materials? How ultrasonics are used for nondestructive testing? [5M]

7.

Write, in detail, any four engineering applications of ultrasonics.

[5M]

8.a) b)

What is SONAR? Explain. The speed of ultrasonics in a medium is 340 m/sec. If the frequency is 6 MHz, find the wavelength of ultrasonics.

[5M]

9.a) b) 10

Explain the term ‘reverberation of sound’ in the case of an auditorium, and hence define the period of reverberation. Derive Sabine’s formula for reverberation time. [5M] Explain how the reverberation time of a hall is affected by: i) its size, ii) surface of walls, iii) ceiling and iv) audience.

[5M]

11.a) Relating to sound, what is absorption coefficient of a material? Explain. b) The volume of an auditorium is 9500 cubic metres. The time of reverbera-tion is found to be 1.5 seconds. Calculate the total absorption in the auditorium, in sabines. If the floor of the auditorium is now covered with carpets whereby the total absorption is found to have increased by 100 sabines, calculate the new time of reverberation. [5M] 12

What are acoustic materials? Explain their role in improving the acoustic quality of an auditorium. [5M]

13

Describe a method to measure the sound absorption coefficient of a material. [5M] Contd…2

::2:: 14

Explain the acoustical defects, generally encountered, in auditoria.

15

Explain the acoustic requirements of a good auditorium. How these requirements can be achieved? [5M] -------

[5M]