AP State Syllabus AP Board 7th Class Science Solutions Chapter 5 Temperature and Its Measurement Textbook Questions and Answers.
AP State Syllabus 7th Class Science Solutions 5th Lesson Temperature and Its Measurement
7th Class Science 5th Lesson Temperature and Its Measurement Textbook Questions and Answers
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The body temperature of Srinath is 99°F. Is he suffering from fever? If so, why?
- Yes, Srinath is suffering from fever.
- The normal temperature of human body is 98.6°F.
- As Srinath has a temperature of 99 °F. It is fever.
Why do we use Mercury in the thermometer? Can water be used instead of Mercury? What are the problems in using it?
- Mercury is used in the thermometer because its expansion is uniform.
- It is opaque and shining.
- It does not stick to the sides of the glass tube.
- It is a good conductor of heat.
- It is easily available in pure state.
- Water cannot be used instead of mercury.
- Water cannot expand as much as mercury expands for a small rise in temperature.
- Water is not opaque and shining.
- Water sticks to the sides of the glass tube.
The temperature of Srinagar (J&K) is -4°C and in Paderu (AP) is 3°C which of them has greater temperature? What is the difference between the temperatures of these two places?
- Paderu (A.P.) has a greater temperature. Its temperature is 3°C.
- The difference between the temperatures of these two places is
= 3 °C – (- 4 °C) = 7 °C.
During winter mornings why do people stand in the Sun? Explain.
- In winter the temperature of the atmosphere in the mornings will be very less than the body temperature of the people.
- So heat from the people flow from their body to the atmosphere.
- People feel quite chill.
- If people stand in the sun in morning the heat radiations from the sun reaches the body of people preventing the flow of heat from their bodies to the atmosphere.
- People feel warm if they stand in the sun.
After walking some distance on a hot summer day, why do we prefer to go into the shade?
- When we walk on a hot summer day we get heat in two ways.
a) Direct heat radiation from the sun and
b) Reflected heat radiation from the surroundings.
- So we feel very hot.
- To get relief from this hotness we prefer to go into the shade, where we get only reflected heat radiation.
Srikanth takes a sip of cold drink and feels the chill. Guess what its temperature is? Try to measure it.
- The temperature of the cold drink maybe 10 °C.
- The normal temperature of the human body will be 37 °C.
- The cold drink is at 10 °C and so Srikanth feels the chill.
- When I measured the temperature of the cold drink I find it at 11 °C.
Jyothi was prepared to measure the temperature of hot water with a clinical thermometer. Is it right or wrong. Why?
- Jyothi was wrong.
- The clinical thermometer can read temperatures between 5 °C to 45 °C.
- The temperature of hot water may be more than 45 °C.
- If the clinical thermometer is put in hot water, mercury in it expands beyond the limit and the thermometer may break.
Swathi kept a laboratory thermometer in hot water for some time and took it out to read the temperature. Rani said it was a wrong way of measuring temperature. Do you agree with Rani? Explain your answer.
- As Rani said, it is a wrong way of measuring temperature.
- In laboratory thermometer there will be no kink in the capillary tube.
- When the thermometer is taken out of hot water, mercury level in the thermometer fall down as there is no kink in the capillary tube near the bulb to prevent the level of mercury falling on its own.
Why do we jerk a clinical thermometer before we measure body temperature?
- The kink in the capillary near the bulb of the clinical thermometer prevents mercury level from falling on its own.
- Before we measure body temperature, we should bring the mercury level to the minimum.
- This is possible only by giving a jerk to the thermometer to bring back the mercury level in it to the minimum.
Heat energy is converted into other forms of energy. Give some examples.
- If we use electric heater to heat water electrical energy is converted into heat.
- If we use a gas stove, chemical energy is converted into heat.
- In solar heaters, solar energy is converted into heat.
Prathima said ‘Heat is a form of energy. How do you support her? Give some examples.
- ‘Heat is a form of energy’. I support Prathima.
- One form of energy can be converted into another form .
- Heat energy can be converted into mechanical energy, electrical energy, etc.
- Energy can do work. With heat we can do several works.
- So heat is a form of energy.
1) When we stand in the sun or near fire, heat energy enters our body and we feel hot.
2) When ice is put on our palm, heat energy moves from our body to the piece of ice. That’s why we feel cold.
Why is a clinical thermometer not used to measure the temperature of air?
- Clinical thermometer is meant to measure our body temperature.
- It can measure temperatures in between 35 °C to 45 °C.
- The temperature of air may not be in these limits.
- So clinical thermometer is not used to measure the temperature of air.
Fill in the blanks.
a. Doctor uses ——– thermometer to measure the human body temperature.
b. At room temperature Mercury is in ——– state.
c. Heat energy transfer from ——– to ——–.
d. – 7 °C temperature is ——– than 0 °C temperature.
c) higher temperature, low temperature
Match the following.
Use the Thermometer and record the temperature in your school daily at mid day meals time in the following table. Record temperature for a month.
a) On which day was the temperature highest? What could be the reason?
b) On which day was the temperature lowest? What could be the reason?
c) What was the average temperature during the month?
This experiment can be done by the student with the help of the teacher.
Draw the diagram of a clinical thermometer and label its parts. What is the use of kink in clinical thermometer?
Use: Kink prevents the Mercury level from falling on its own.
Draw the diagram of a laboratory thermometer and label its parts. How does it differ from a clinical thermometer?
It differs from a clinical thermometer in many ways.
a) This thermometer has no kink in the capillary near the bulb.
b) This thermometer has graduations from – 10 °C to 110 °C where as clinical thermometer has graduations from 35 °C to 45 °C.
Measure the body temperature between fingers, under the tongue, armpit, folded hands, folded legs etc. Is it the same? Does the body temperature remain the same after jumping ten times? Why?
- The temperature measured between the fingers, under the tongue, armpit, folded hands, folded legs etc. are not the same.
- Real temperature of the body is recorded as true when recorded under the tongue.
- At other places mentioned the temperature recorded differ from the temperature taken under the tongue.
- Temperature taken in folded legs also do not coincide with other temperatures recorded as some additional heat may be stored due to folding of legs.
Collect information from hospital/health centre about the precautions to be taken while reading temperature with a clinical thermometer.
Precautions to be taken:
- Thermometer should be washed before and after use preferably with an antiseptic solution.
- Ensure that before the use the mercury level is below 35 °C.
- Read the thermometer keeping the level of mercury along the line of sight.
- Handle the thermometer with care.
- Do not hold the thermometer by bulb while reading it.
Measure the temperature of water in normal conditions. If you add the following substance to the water, do you find any difference in temperature? Predict and verify.
Do you find any change in temperature before and immediately after mixing the above substances in water? If yes, what could be the reason?
The student is advised to do this with the help of the teacher and record the observations.