2. Give reason for the following a) Table mats are made from plastics. b) We cannot use laboratory thermometer to measure our body temperature. c) Solar cooker are painted black from inside. d) We prefer to wear white cloth in summer. e) The mercury is chosen as thermometric liquid. f) Stainless steel cooking utensils are usually provided with copper bottoms. g) Shopkeeper selling ice blocks usually cover them with jute bags. (h) Deserts are very hot during day and cold at night. (i) Double walled containers are used to make ice boxes.
Answers
Answer:
Answer:
a)Table mats are usually made up of canes or plastic because canes or plastics are easy to clean and are also cheaper. They are also very convenient to use. ... Moreover, plastics are bad conductor of heat, so during summer they don't heat more when kept under sun.
b)laboratory thermometer cannot be used to measure the temperature of a human body because the range of a laboratory thermometer is high generally from –10°C to 110°C, while as normal body temperature in humans is only 37°C.
c)This property is used in solar cooker where sunlight beats on the device and due to its black color more heat is absorbed. Solar cooker are painted black to maximize the absorption of heat from the sun.
d)We prefer to wear light coloured clothes in summer as light colours reflect light and heat and as a result of which light coloured clothes absorb less heat and become less hot giving us relief in summers.
e) Because Mercury is the only one in liquid state at room temperature. It's used in thermometers because it has high coefficient of expansion. Hence, the slightest change in temperature is notable when it's used in a thermometer. It also has a high boiling point which makes it very suitable to measure higher temperatures.
f)Stainless steel is generally provided with a copper bottom because copper is a very good conductor of heat and electricity. Thus, it helps in directing the heat evenly throughout the utensil, and heats the steel pans faster. So cooking process will take less time with these copper coated steel pans.
g)Shopkeepers selling ice blocks usually cover them with jute sacks as jute bags are bad conductors of heat. The don't allow heat to enter the bag thus the ice wont melt.
h)Deserts are cold during the night because of the sand. Because sand cannot hold heat, it needs a constant source of energy to stay warm (The Sun). so during the night when the sun is not shining the sand loses all its heat, making the desert night cold.
I)Double walled container are used to make ice box because the space two wall is kept with a vacuum which provides a insulation cover to the inner box, therefore the outer heat of the box can't after inside the box and melt theice.
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