Temperature And Its Measurement: It is possible to identify whether the object is hot or cold with the help of temperature. The apparatus commonly used in the laboratory to show expansion on heating is the ring and ball apparatus. (d) all of these. Thus, a chemical change occurs in the vegetables. The apparatus commonly used in the laboratory to show expansion on heating is the ring and _________ apparatus. If overhead electric cables are being laid in summers, should they be tightened up, or left a little loose? Download app, watch sample animated video lessons and get a free trial. Because the Celsius scale has 100 divisions in total. Heat energy is basically the energy of the movement of molecules. However, he knows that expansion on heating is a fact of life and cannot be done away with. We have received your request successfully. (d) 18°F rise in temperature, Temperature is measured by expansion on heating. °F = 32, A bimetallic strip is made of metals M1 and M2. Heat causes 1 = (95)C2  - (95)C1 Equation to convert oC to oF is as follows: All questions and answers from the Living Science 2019 2020 Book of Class 7 Science Chapter 5 are provided here for you for free. Class-7CBSE Board - Temperature and Its Measurement - LearnNext offers animated video lessons with neatly explained examples, Study Material, FREE NCERT Solutions, Exercises and Tests. However, temperature cannot flow from one object to the other. Therefore, when fire will reach this bimetallic strip, the brass will expand more thereby bending it towards the iron strip. Can a clinical thermometer be used to measure the temperature of boiling water? The mercury moves toward the partly-filled bulb and pushes up the index in the capillary closer to the partly-filled bulb. Living Science 2019 2020 Solutions for Class 7 Science Chapter 5 Heat And Its Effect are provided here with simple step-by-step explanations. This will save the cables from tearing when they start contracting in winters. When the strip is heated, it will (c) gas Which of these will expand the most on heating? What precautions are taken to make sure this expansion does not damage the bridge? Because the molecules of gases are not bound to each other, the vibration of molecules increases when gases are heated. F2 - F1 = [(95)C2 + 35 ] - [(95)C1 + 35] A cold object contains minimal heat energy as compared to our body, so when we touch a cold object, heat from the higher energy region, i.e., our body, flows to the lower energy region, i.e., the cold object. In gases, molecules are not bound at all, so they expand maximum upon heating. After cooling back the liquid to its normal temperature, the level will drop again. On heating, gases expand the most. Class 7 ; Class 8 ; Class 9 ; Class 10 ; Class 12 ; Online Labs . If this is not done, it will only cause serious damage to the bridge. (a) heat flows from your body to the object A clinical thermometer cannot be used to measure high temperatures because it has been designed to measure only human body temperature which varies over a short range. (2) We can use long welded rails(LWR) and continuously welded rails(CWR). It should be kept upright while reading the temperature. One of its end is fixed and the other end is made to rest on rollers with enough space for expansion. (d) none of these. You will also love the ad-free experience on Meritnation’s Living Science 2019 2020 Solutions. This is because heat can be converted into other forms of energy, and many other forms of energy can be converted into heat energy. 1) A measure … Hence, for the same temperature increase, the increase on the Celsius scale is only by 0.56o, while that on the Fahrenheit scale is by 1o. Between Celsius and Fahrenheit scales which one is more convenient to use? Ensure that the mercury level is below 35. On the Fahrenheit scale, the upper fixed point is 212o F, which is equivalent to 100oC on the Celsius scale. Which of these expand the most on heating−solids, liquids or gases? 2. Hence, it is less likely to crack. A bimetallic strip consists of two metal strips, one of iron and the other of brass, bolted together firmly. Once the solids are cooled back to 0oC, the molecules stop vibrating, thereby returning to their specific positions. Talk about three of these changes. (c) 32°F (d) 100°F, (c) 32o F                x = 109x - 1609 Toll-free 1800 419 1234 ( Everyday 11am - 8pm ), Or call us at 1800-419-1234 (toll free) on anyday, 11am - 8pm, JavaScript and Adobe Flash 9 or above are required to view this video.                - 19x = - 1609 Due to this, the average distance between the molecules also increases, thereby increasing the volume of the substance, i.e., expanding the substance. This is the reason why one end of a steel bridge is fixed and the other rested on rollers with enough space on its front to allow it to expand easily. But the boiling point of water is 100oC. (d) temperature flows the object to your body. Temperature is usually measured by measuring expansion in gases since gases expand the most. Sterilise the thermometer using an antiseptic solution before and after its use. oF = 45 + 32 Hence, when the temperature is 160oC, then on the Fahrenheit scale it will be 320oF. Take a rubber cork with a hole in it and insert a glass tube in it. However, the movement of molecules depends upon the state of matter. Temperature and its Measurement : The video explains how to measure the temperature using thermometers. Hence, the order of expansion can be written as: Gases > Liquids > Solids. Hotter the body, higher is its temperature. 2. (b) of the increase in the movement of molecules Give reasons. We get,   x = (59)(2x-32) Explain the working with the help of a labelled diagram. The molecules of solids are tightly packed. It should be handled with care, as it is made up of a glass tube. Book an appointment now! Why is a laboratory thermometer not used to measure body temperature? (b) change of temperature * For your record, an e-mail and SMS has been sent to you with these details. Due to this bending of the strip, the circuit for the electric bell is completed and it starts ringing as the fire alarm. Solids have tightly packed molecules; hence, least movement of molecules takes place leading to minimal expansion. Kelvin temperature scale is used for scientific purposes. That's why its easier to measure, calculate and convert the temperature on the Celsius scale. (d) air 1 = (95)[C2 - C1] The kink in the stem prevents the mercury from falling back immediately, thereby giving us the accurate reading of our body temperature. And, after returning to the room temperature, the strip straightens as before. Explain why a substance expands on heating. A thick walled tumbler will crack more easily than a thin walled tumbler when extremely hot or cold water is poured into them.This is because in a thick walled glass, it's outer wall will be less affected by the extreme temperature as compared to its inner wall.