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Tamil Nadu Board 12th Standard Physics - Unit 5: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 5 from the Tamil Nadu State Board 12th Standard Physics textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Unit 5 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 12 students! Prepare well and aim for top scores. Thank you!

I. Multiple choice questions.

1. A plane glass is placed over a various coloured letters (violet, green, yellow, red) The letter which appears to be raised more is,
(a) red 

(b) yellow
(c) green 

(d) violet

Answer Key:

(d) violet

  
2. Two point white dots are 1 mm apart on a black paper. They are viewed by eye of pupil diameter 3 mm approximately. The maximum distance at which these dots can be resolved by the eye is, [take wavelength of light, λ = 500 nm]
(a) 1 m 

(b) 5 m
(c) 3 m 

(d) 6m

Answer Key:

(b) 5 m 

  
3. In a Young’s double-slit experiment, the slit separation is doubled. To maintain the same fringe spacing on the screen, the screen-to-slit distance D must be changed to,
(a) 2D 

(b) $\frac{\mathbf{D}}{\mathbf{2}}$
(c) $\sqrt{\mathbf{2}}\mathbf{D}$

(d) $\frac{\mathbf{D}}{\sqrt{\mathbf{2}}}$
Answer Key:

(a) 2D  

 
4. Two coherent monochromatic light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are [IIT-JEE 1988]
(a) 5I and I  

(b) 5I and 3I
(c) 9I and I

(d) 9I and 3I

Answer Key:

(c) 9I and I 

  

5. When light is incident on a soap film of thickness 5×10 ${\mathbf{10}}^{\mathbf{-}\mathbf{5}}$ cm, the wavelength of light reflected maximum in the visible region is 5320 Å. Refractive index of the film will be,

(a) 1.22 

(b) 1.33
(c) 1.51 

(d) 1.83.

Answer Key:

(b) 1.33 

 
6. First diffraction minimum due to a single slit of width 1.0×10 ${\mathbf{10}}^{\mathbf{-}\mathbf{5}}$ cm is at 30o. Then wavelength of light used is,
(a) 400 Å 

(b) 500 Å
(c) 600 Å 

(d) 700 Å

Answer Key:

(b) 500 Å 

 
7. A ray of light strikes a glass plate at an angle 60o. If the reflected and refracted rays are perpendicular to each other, the refractive index of the glass is,
(a) $\sqrt{\mathbf{3}}$

(b) $\frac{\mathbf{3}}{\mathbf{2}}$
(c) $\sqrt{\frac{\mathbf{3}}{\mathbf{3}}}$
(d) 2

Answer Key:

(a) $\sqrt{\mathbf{3}}$ 

 
8. One of the of Young’s double slits is covered with a glass plate as shown in figure. The position of central maximum will, 

 (a) get shifted downwards
(b) get shifted upwards
(c) will remain the same
(d) data insufficient to conclude

Answer Key:

(b) get shifted upwards

 
9. Light transmitted by Nicol prism is,
(a) partially polarised
(b) unpolarised
(c) plane polarised
(d) elliptically polarised

Answer Key:

(c) plane polarised

  

10. The transverse nature of light is shown in,
(a) interference
(b) diffraction
(c) scattering
(d) polarisation 

Answer Key:

(d) polarisation 

  

II. Short answer questions.

12th Physics

III. Long answer questions. 

12th Physics

IV. Exercises.   

12th Physics