Tiêu đề Thermal EXpansion (M.C.Q.) E.pdf ✅

PHYSICS Q. 1 The temperature of an isotropic cubical solid of length L, density , and coefficient of linear expansion  per kelvin is raised by 10oC. Then at this temperature to a good approximation. (A) Length is L(1 + 10) (B) total surface area is L2 (1 + 20) (C) density is (1 + 30) (D) density is +   1 30 [A,D] Q.2 Three identical rods of same material are joined to form a triangular shape ABC as shown. Angles at edge A and C are respectively 1 and  as shown. When this triangular shape is heated then - A B C   (A) 1 decreases and 2 increases (B) 1 increases and 2 decreases (C) 1 increases (D) 2 increases [C,D] Sol. In thermal expansion all dimensions will increases. Q.3 Which of the following statements is correct ? (A) Bimetal is used in metal thermometers (B) Bimetal is used in thermostats for regulating the heating or cooling of rooms (C) Bimetal relays are used to open or close electric circuits. (D) Bimetals are used to generate electricity [A,B,C] Q.4 If ,  and  are coefficients of linear, superficial and volume expansion respectively, then– (A) 2 1 =   (B) 3 2 =   (C) 1 3 =   (D)   =   [B,C] Q.5 A bimetallic strip is formed out of two identical strips, one of copper and the other of brass. The coefficient of linear expansion of the two metals are C and B . On heating, the temperature of the strip goes up by T and the strip bends to form an arc of radius of curvature R. Then R is – [IIT–99] (A) Proportional to T (B) Inversely proportional to T (C) Proportional to |B – C | (D) Inversely proportional to |B – C | [B,D] Q.6 When the temperature of a copper coin is raised by 80oC, it's diameter increase by 0.2% - (A) Percentage rise in the area of a face is 0.4% (B) Percentage rise in the thickness is 0.4% (C) Percentage rise in the volume is 0.6% (D) Coefficient of linear expansion of copper is 0.25 × 10–4 /oC [A,C,D] Sol. A A × 100 = 2       A  × 100  % increase in Area = 2 × 0.2 = 0.4 V V × 100 = 3 × 0.2 = 0.6% Since  =   T   × 100 =  T × 100 = 0.2   = 0.25 × 10–4 /oC Q.7 A driver of an automobile gets his gasoline tank made of steel of volume 75L, filled with 75 L of gasoline at 10°C. As the temperature in the day becomes 30°C - [steel = 12 × 10–6 /°C, gasoline = 9.5 × 10–4 /°C] (A) Change in volume of gasoline is 190 L (B) Change in volume of steel tank is 0.054 L (C) Gasoline overflow is 1.37 L (D) Gasoline will not overflow [B,C] Sol. V = V0T = V0(3  T) If change in volume for gasoline is more than that of tank it will overflow.