Q1. How to read a clinical thermometer?
Ans: Reading a Clinical Thermometer
There are following steps to read the temperature on a thermometer.
Q2. What precautions should we take to read a clinical thermometer?
Precautions while Reading the Thermometer: A clinical thermometer should not be used for any object other than the human body. There are some following precautions which are to be observed while reading a clinical thermometer.
Q3. List any four effects of heat. Explain them.
Ans: When heat energy is absorbed by a body various changes can happen. Some of them are:
Q4. Instead of water explain the reason, why do the mercury is used in the thermometer?
Ans: Due to following reasons, mercury is used in the thermometers instead of water
Q5. The clinical thermometer is not used to measure high temperature. Why? Also State the limitation of clinical thermometer.
Q6. Differentiate between two modes of transfer of heat, i.e. convection and conduction.
Ans: Difference between convection and conduction
Q7. Observe the picture given in figure. Water is being boiled in a pan of wide base.
(a) Which position P or T will feel warmer?
(b) Fill up the boxes P and T to indicate the mode of flow of heat to the hand.
(a) As in the given diagram, position P will feel warmer because of heat, air rises.
(b) The flow of heat to P is a convection process and flow of heat to T is radiation.
Q8. Explain the differences between heat and temperature.
Ans: The differences between heat and temperature are given as below
Q9. Prove with the help of an experiment that heat radiation can travel through vacuum.
Ans: First of all, take a flat bottom flask and fix a rubber stopper having two holes in the mouth of the flask. Shift a thermometer through one hole and a glass tube with stopper through the other hole. Now, with the help of a vacuum pump, remove the air from the flask and try to record the temperature from the thermometer. Put a flask in the bright sunlight and we will observe that the thermometer records a rise in temperature. So, on this basis, we can say that this experiment proves that the heat radiation can travel through vacuum.
Q10. Describe in detail about the occurrence of oceanic currents.
Ans: Since, it is a fact that the water present in the ocean (near the equator) is heated by the sun to a very higher temperature than the water near the poles of the earth. It is due to the falling of the sun rays perpendicularly in the equatorial region. So, in the equatorial region, the ocean water expands and becomes lighter.
While on the other side, the water in the polar region remains cold and heavy. It leads to the flow of convection currents of heat of warm water from the equator towards the poles.
Heat of the cold water flow from the poles towards the equator just below the surface of ocean. So, these types of currents are known as oceanic currents.
Q11. Write about clinical thermometer. What is laboratory thermometer?
Q12. What are the differences between temperature and heat?
Q13. Write any three precautions to be taken while reading a clinical thermometer.
Q14. Can a clinical thermometer be used to measure the temperature of boiling water?
Ans: No, a clinical thermometer cannot be used to measure the temperature of boiling water because the temperature of boiling water is more than the fixed range of the clinical thermometer, i.e., 42°C. If we try to measure the temperature of boiling water, it will break down.
Q15. Explain how the temperature of water can be measured by using a laboratory thermometer.
Ans: To measure the temperature of water by using a laboratory thermometer, we follow the following steps:
Q16. What is temperature? Describe two types of thermometers used to measure the temperature.
Ans: A reliable measure of the hotness of an object is called its temperature. It is measured by a device called thermometer.
There are two types of thermometer:
(i) Clinical thermometer: The thermometer that measures the temperature of our body is called clinical thermometer. It consists of a long, narrow, uniform glass tube. It has a bulb at one end which contains mercury. Outside the bulb a small shining thread of mercury can be seen. There is also a scale on the thermometer. The scale used in it is the celsius scale, indicated by °C. A clinical thermometer reads temperature from 35°C to 42°C.
(ii) Laboratory thermometer: This type of thermometer is used to measure the temperature of different objects in laboratories. It is made of a thin glass tube sealed at one end and a bulb with mercury at the other end. The portion of the capillary tube above the bulb is graduated in degrees usually from -10°C to 110°C.
Q17. What do you mean by transfer of heat? Explain the process of transfer of heat in solids, liquids and gases.
What do you mean by transfer of heat? Explain the process of transfer of heat.
Ans: Flow of heat from one object to another whether solid or liquid is called transfer of heat. Heat always flows from a body at higher temperature to another body at lower temperature. In other words, heat always flows from a hotter body to a colder. In this process, the temperature of hot body falls as it releases heat which is received by the colder body or a body having lower temperatures. Thus the temperature of the colder body or less hotter body rises. The flow of heat stops when temperature of both the bodies becomes equal.
Transfer of heat take place through conduction, convection and radiation. Conduction is the process of transfer of heat from one particle to the next particle in a solid without the particles actually moving from their position.
Convection is the process of heat transfer in which the particles change their positions by constantly moving from the hotter region to the cooler region, thus causing heat energy to flow. In convection heat travels through the liquids and gases.
Radiation is the process of heat transfer from a hot body to a colder body without any medium between the two.
Q18. Explain the term radiation.
Explain how can heat travel in vacuum or without medium.
Ans: The heat from the sun cannot reach us by conduction or convection as there is no medium such as air in most part of the space between the earth and the sun. This is possible through the process of radiation. The mode of transfer of heat energy in which no medium is needed to transfer heat from a hotter body to a colder body is called radiation. It can take place whether a medium is present or not. For example, when we sit in front of a room heater we get heat by this process.
A hot utensil kept away from the flame cools down as it transfers heat to the surroundings by radiation. Our body too, gives heat to the surroundings and receives heat from it by radiation. The figure below show the radiation by the sun. It also shows that when radiation falls on an object a part of it is reflected, a part is absorbed and a part may be transmitted.
Q19. How does the heat travel in air? Explain the sea breeze and land breeze in coastal areas in this reference.
Ans: Heat travels in air through the process of convection. The air near the heat source gets hot and rises up. The cool air from the sides comes in to take its place. In this way the air gets heated up.
In the coastal areas, people experience an interesting phenomenon. The land gets heated faster than the water during the day. The air over the land becomes hotter and rises up. The cooler air from the sea rushes in towards the land to take its place. The warm air from the land moves towards the sea to complete the cycle.
The flow of cool air from the sea towards the land to replace the hot air on land, is called sea breeze. At night it is just the reverse: The water cools down more slowly than land. So the cool air from land moves toward the sea. This is called land breeze.