NCERT Solutions for Class 7 Science Chapter 4 - Free PDF Download
1. State similarities and differences between the laboratory thermometer and the clinical thermometer.
Ans: Similarities include the use of mercury and the measurement of temperature.
Differences include clinical thermometers have a kink to prevent the temperature from dropping, but laboratory thermometers do not have a kink.
In comparison to clinical thermometers, the range of a laboratory thermometer is extremely broad.
2. Give two examples each of conductors and insulators of heat.
Ans:
3. Fill in the blanks:
a. A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of ________.
Ans: Conduction.
b. Temperature is measured in degrees _________.
Ans: Celsius.
c. No medium is required for transfer of heat by the process of _________.
Ans: radiation.
d. Clothes of _________ colours absorb heat better than clothes of light colours.
Ans: black
e. The hotness of an object is determined by its _________.
Ans: Temperature.
f. Temperature of boiling water cannot be measured by a __________ thermometer.
Ans: clinical
4. Match the following:
i. Land breeze blows during a. summer
ii. Sea breeze blows during b. winter
iii. Dark coloured clothes are
preferred during c. day
iv. Light coloured clothes are
preferred during d. night
Ans:
5. Discuss why wearing more layers of clothing during winter
Ans: When more than one layer of clothing is worn, air gets trapped between them. Heat does not transmit well through air. As a result, the insulation improves and we are more comfortable.
6. Look at Fig. 4.2. Mark where the heat is being transferred by conduction, by convection and by radiation.
Ans:
7. In places of hot climate, it is advised that the outer walls of houses be painted white. Explain.
Ans: White-surfaced objects radiate more heat and absorb less. As a result, less outside heat would enter the house.
8. One liter of water at 3000C is mixed with one liter of water at 5000C. The temperature of the mixture will be
a. 8000C
b. More than 5000C
c. 2000C
d. Between 3000C and 5000C
Ans: d. The temperature lies between 3000C to 5000C. As it is a mixture of waters boiled at two different temperatures.
9. An iron ball at 4000C is dropped in a mug containing water at 4000C the heat will
a. Flow from iron ball to water.
b. Not flow from iron ball to water or from water to iron ball.
c. Flow from water to iron ball.
d. Increase the temperature of both.
Ans: b. Not flow from iron ball to water or from water to iron ball. It is due to the fact that both the substances, the water and the iron have the same temperature.
10. A wooden spoon is dipped in a cup of ice cream. Its other end
a. becomes cold by the process of conduction.
b. becomes cold by the process of convection.
c. becomes cold by the process of radiation.
d. does not become cold.
Ans: d. does not become cold. Heat conducts poorly through a wooden spoon. Its opposite end does not grow cold even if it is dipped in a cup of ice cream.
11. Stainless steel pans are usually provided with copper bottoms. The reason for this could be that
a. Copper bottom makes the pan more durable.
b. Such pans appear colourful.
c. Copper is better conductor of heat than the stainless steel.
d. copper is a better conductor of heat than the stainless steel.
Ans: c. Copper is a better conductor of heat than stainless steel. Copper bottoms are commonly included with stainless steel cookware. Copper is a superior heat conductor than stainless steel, which could be the reason.
NCERT Solutions for Class 7 Science Heat – Free PDF Download
Aspirants will be able to download CBSE Class 7 Science Chapter 4 as per their convenience and requirements. They can also refer the notes to their friends to make learning more gratifying. Students, through the notes provided, will be able to gain crucial insight into the chapters. NCERT Solution for class 7 science chapter 4 is prepared by the best teachers and easy to understand.
Chapter 4 – Heat
4.1 Hot and Cold
While performing our daily tasks, we often need to touch a number of objects, among which some are cold and hot. Obviously, an iron rod exposed to the sun for longer period becomes hot and an ice-cream stored in the refrigerator stays cool. Without noticing, we keep playing between hot and cold. Now, the degree of temperatures varies depending on the situation and objects. So, how is it possible to determine which objects are hotter than others? Naturally, by touching the object it is possible to figure out, but finding accuracy in temperature can become a problem.
4.2 Measuring Temperature
Have you ever seen a thermometer? It is quite natural to get your hands on one of them when someone in your family suffers from fever. A thermometer is used for measuring the temperature of our body. There are different types of thermometer available. What we see commonly in our house is a clinical thermometer. It is used for measuring the body’s temperature only. A clinical thermometer looks like a cylindrical pipe made of glass. A bulb containing mercury stays attached at the bottom. Outside the bulb, you can notice a small shining thread of mercury. If it’s hard to locate, considering rotating the thermometer slightly to see the meter. It is usually seen through the two meeting end of the thermometer’s radius. The scale used for the clinical thermometer is measured in °C.
When reading a thermometer, make sure to note the difference in temperature indicated by two bigger marks. Also, you can note the number of divisions. If a bigger mark reads one degree and it is divided into five divisions, it indicates 1/5 = 0.2 °C. Before using a thermometer, give it some nice jerks so that the mercury accumulates down at the bulb and prevent wrong readings. Now, place the thermometer under the tongue or underarm. After one minute precisely, take out the thermometer and note down the temperature. It is our natural body temperature. Our normal body temperature should be around 37°C.
Important Note: Thermometer must be prevented from receiving falling as it is made of glass. Also, it can be harmful if the mercury leaks out. Do not hold a thermometer by the bulb when reading.
4.3 Laboratory Thermometer
Now, let’s understand how is it possible to take readings from other objects. For this, we need laboratory thermometer. The teacher can probably show you a laboratory thermometer from the chemistry lab. Here, the range of measuring scale differs from that of a clinical thermometer. A lab thermometer’s measuring scale typically ranges from -10°C to 110°C. Each reading should be noted to discern correct information of an object.
Interesting Facts
The thermometers what we see today are an advanced form of traditional thermoscopes. It was first invented by the famous scientist Galileo Galilei. At first, he used a device that looked like an open tube filled with liquid. However, despite evolution, some of the numerical scales for measuring temperatures are still the same. The Fahrenheit and Celsius scales are mostly used for measuring different types of temperatures. Interestingly, there were more than 35 scales designed by 1700s, but finally, conclusions were made by Daniel Fahrenheit and Swedish physicist Anders Celsius. Daniel Fahrenheit assigned the boiling point of water at 212 degrees and the freezing point at 32 degrees. In 1742, Anders Celsius developed the centigrade scale and therefore, assigned the boiling point of water at 0 degrees and the melting point of ice at 100 degrees. The new age Celsius scale is generally popular with 0 degrees at the cold end and 100 degrees at the hot end. Remember, Fahrenheit and Celsius’s scale are same when each comes at the point of -40 degrees.
Other popular scales that are used for laboratory works are Kelvin and Rankine scales. In 1848, British inventor Lord Kelvin, officially known as William Thompson proposed a scale using the Celsius measurement. However, it was keyed to absolute zero (-273.15°C). Looking at the Rankine scale, it was invented by Scottish engineer William Rankine. He, in his research, used the Fahrenheit’s scale and keyed down to absolute zero (-459.67 °F). It is important to keep in mind that when it comes to theoretical temperature, absolute zero is the coldest reading in any substance that does not possess any heat energy.
4.4 Transfer of Heat
Have you ever thought why a frying pan becomes hot when placed on a source of flame? This happens due to the transfer of heat. The heat from the source passes to through the frying pan and cooks the food inside it. Gradually, it starts cooling down when removed from the source of heat. Again, why does it cool down? The heat escapes from the pan by transferring through the floor or anything that touches it. Therefore, it is clear that heat flows from hotter objects to cooler ones. The same happens even in the case of nature that builds the cycle of heat and rain.
4.5 Kinds of Clothes We wear in Summer and Winter
It is common for us to wear light coloured clothes in the time of summer and dark coloured clothes during winter. The reason behind this is its scientific cause. Anything which is light coloured absorbs less heat and reflects more. During the daytime, consider standing in front of a building that is painted white. It’s good if it is newly painted and the colour is glossy. You will notice that standing in front of the building for a long time isn’t possible. Also, the interior of the building remains relatively cooler when compared with other buildings. This is because light colours absorbs less heat and reflect more. On the contrary, the occupants in the building may feel the shiver during winter months. As light colours are unable to absorb more heat, they remain cool even during cold weather. For this reason, it is said to always wear dark coloured clothes during winter so that the heat inside our body cannot escape. It also helps us in preventing the natural and colder breeze from entering in and making our body cold.
Woollen Clothes Keep us Warm in Winter
Why do woollen clothes provide warmth in winter seasons? This is because wool is a bad conductor of heat. The fibres of wool help in keeping the air trapped inside and thus, keep the cold out. The trapped air stops the movement of heat to cold surroundings. Therefore, it is competent in keeping us warm. In a winter night, if you use a couple of blankets to make yourself warm, it will be a lot effective when compared with someone who is using a single blanket. This is not because of mere number count. The fact is, the air which is trapped between the two blankets, keeps you warm and prevents cold to enter in.
NCERT Solutions Class 7 Science Chapters
Key Features of NCERT Solutions for Class 7 Science Chapter 4
Vedantu is considered as a reliable platform for various study tools for different classes under CBSE board.
NCERT Class 7 Science Chapter 4 Solutions are tailored by experienced and skilled teachers who are committed to helping students.
The teaching approach helps students to learn Heat Chapter Class 7 faster and better.
The study materials covered all topics of NCERT Class 7 Science Chapter 4.
The solutions provided by expert faculty team help in the improvement, especially when fine-tuning becomes crucial before exams.
The study materials will provide an upper hand to compete on merit level.
Important Points
Heat is a type of energy that causes a substance to become hot. In the winter, it is typical to feel cold inside the house and warm outside when exposed to the sun's rays.
In our daily lives, we come across a variety of items, some of which are hot and others which are cold, such as when a frying pan on a hot gas burner becomes heated while the pan's handle remains cool.
The temperature of an object is the degree of hotness or coldness of the object. The temperature of a thing is the only property that distinguishes between hot and cold objects.
Conclusion
The NCERT Solutions for Class 7 Science Chapter 4 - Heat offers a comprehensive and detailed understanding of the fundamental principles of heat and its various applications. Through these solutions, students have gained insights into concepts such as temperature, thermal expansion, modes of heat transfer, and the importance of heat in everyday life. By engaging with these solutions, students have not only strengthened their theoretical knowledge but also developed practical problem-solving skills. The chapter's emphasis on real-life examples and practical exercises has enabled students to grasp the significance of heat in the natural world and its relevance to modern technology. Overall, NCERT Solutions have been instrumental in fostering a deeper appreciation for the science of heat and its broader applications in the world around us.
FAQs on NCERT Solutions for Class 7 Science Chapter 4 - Heat
1. What is the name of Chapter 4 of Class 7th Science?
The name of Chapter 4 of Class 7th Science is ‘Heat’. This chapter will stress upon and discuss in detail how the transfer of energy occurs and its significance. The solutions for this particular chapter can easily be found on the Vedantu site along with additional help required by the student for achieving good marks in their exams. The solutions provided by Vedantu are free of cost and also available on Vedantu Mobile app.
2. What is heat according to Chapter 4 of Class 7 Science?
Heat in simple terms is nothing but the transfer of energy. It helps in maintaining thermal equilibrium, i.e. for having the same temperature when multiple bodies with their different individual temperatures are in contact. Hence for all of them to have the same temperature, energy transfer occurs from the bodies which have the higher temperature to the ones whose temperature is lower. Heat transfer and its processes are very crucial and hence learn the concepts and practice the related problems judiciously.
3. What is a thermometer according to Chapter 4 of Class 7 Science?
A thermometer is a temperature-measuring instrument. It is capable of determining the temperature of a variety of substances, including food, liquids, and gases. Celsius, Fahrenheit, and Kelvin are the three most widely used temperature measuring units in the world. The most accurate technique to check one's body temperature is with a digital thermometer. In addition to the traditional oral, rectal, and forehead, there are also plenty of other options.
4. What do you mean by conductors according to Chapter 4 of Class 7 Science?
The transmission of internal energy via tiny particle collisions and electron movement within a body is known as thermal conduction and the materials that exhibit this propagation are called conductors of heat. Good heat conductors are materials that allow heat to readily flow through them. Metals that exhibit the highest thermal conductivity include copper and aluminium, whereas steel and bronze exhibit the lowest values.
5. What do you mean by insulators according to Chapter 4 of Class 7 Science?
An insulator is a substance that prevents energy from easily passing through it, such as electricity, heat, or cold. Insulators such as wood, plastic, rubber, and glass are effective. The conductor is the polar opposite of an insulator: a substance that easily conducts heat or electricity. Insulators shield humans from the potentially lethal consequences of electricity passing via conductors. An electrical circuit's voltage can be extremely high and harmful at times.