11th Physics - Book Back Answers - Unit 8 - English Medium Guides

 

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Tamil Nadu Board 11th Standard Physics - Unit 8: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 8 – Physics from the Tamil Nadu State Board 11th 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 Physics Unit 8 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 11 students! Prepare well and aim for top scores. Thank you!

Unit 8 :Heat And Thermodynamics

I. Multiple Choice Questions

1. In hot summer after a bath, the body’s
a) internal energy decreases
b) internal energy increases
c) heat decreases
d) no change in internal energy and heat
Answer Key:
a) internal energy decreases

2. The graph between volume and temperature in Charles’ law is
a) an ellipse 
b) a circle
c) a straight line 
d) a parabola
Answer Key:
c) a straight line 

3. When a cycle tyre suddenly bursts, the air inside the tyre expands. This process is
a) isothermal
b) adiabatic
c) isobaric 
d) isochoric
Answer Key:
b) adiabatic

4. An ideal gas passes from one equilibrium state (P₁, V₁, T₁, N) to another equilibrium state (2P₁, 3V₁, T₂,N). Then

a) T₁ = T₂

b) ${\mathrm{T}}_1=\frac{{\mathrm{T}}_2}{6}$ 

c) T₁ = 6T₂

d) T₁ = 3T₂

Answer Key:
b) ${\mathrm{T}}_1=\frac{{\mathrm{T}}_2}{6}$ 

5. When a uniform rod is heated, which of the following quantity of the rod will increase
a) mass
b) weight
c) center of mass
d) moment of inertia
Answer Key:
d) moment of inertia

6. When food is cooked in a vessel by keeping the lid closed, after some time the steam pushes the lid outward. By considering the steam as a thermodynamic system, then in the cooking process
(a) Q > O, W > O,
(b) Q < O, W > O,
(c) Q > O, W < O,
(d) Q < O, W < O,
Answer Key:
(a) Q > O, W > O,

7. When you exercise in the morning,by considering your body as thermodynamic system, which of the following is true?
a) ΔU > O, W > O,
b) ΔU < O, W > O,
c) ΔU < O, W < O,
d) ΔU = O, W > O,
Answer Key:
b) ΔU < O, W > O,

8. A hot cup of coffee is kept on the table. After some time it attains a thermal equilibrium with the surroundings. By considering the air molecules in the room as a thermodynamic system, which of the following is true
a) ΔU > O, Q = O
b) ΔU > O, W < O
c) ΔU > O, Q > O
d) ΔU = O, Q > O
Answer Key:
c) ΔU > O, Q > O

9. An ideal gas is taken from (P_i,V_i)  to (P_f,V_f)  in three different ways. Identify the process in which the work done on the gas the most.

a) Process A

b) Process B
c) Process C
d) Equal work is done in Process A,B &C
Answer Key:
b) Process B

10. The V-T diagram of an ideal gas which goes through a reversible  cycle A→B→C→D is shown below. (Processes D→A and B→C are adiabatic)

The corresponding PV diagram for the process is (all figures are schematic) 

 Answer Key:

11. A distant star emits radiation with maximum intensity at 350 nm. The temperature of the star is
a) 8280 K 
b) 5000K
c) 7260 K 
d) 9044 K
Answer Key:
a) 8280 K 

12. Identify the state variables given here?
a) Q, T, W 
b) P, T, U
c) Q, W
d) P, T, Q
Answer Key:
b) P, T, U

13. In an isochoric process, we have
a) W = 0 
b) Q = 0
c) ΔU = 0 
d) ΔT = 0
Answer Key:
a) W = 0 

14. The efficiency of a heat engine working between the freezing point and boiling point of water is    (NEET 2018)
a) 6.25% 
b) 20%
c) 26.8%
d) 12.5%
Answer Key:
c) 26.8%

15. An ideal refrigerator has a freezer at temperature −12°C. The coefficient of performance of the engine is 5. The temperature of the air (to which the heat ejected) is
a) 50°C 
b) 45.2°C
c) 40.2°C 
d) 37.5°C
Answer Key:
c) 40.2°C 

II. Short Answer Questions

11th physics

III. Long Answer Questions

11th Physics

IV. Exercise

11th Physics