Observe the picture given below. Water is being boiled in a pan of wide base. Which position P or T will feel warmer?

When the air in the vicinity of the boiling water gets heated, its density decreases, and it rises up. The cold air from the surrounding moves towards the boiling water to replace the hot air. This air also gets heated and rises. This process continues, and the mode of heat transfer occurring in this manner is known as convection. Since the hot air is rising up, the position P will be warmer.

Observe the picture given below. Water is being boiled in a pan of wide base. Fill up the boxes P and T to indicate the mode of flow of heat to the hand.

Note: When the air in the vicinity of the boiling water gets heated, its density decreases and it rises up. The cold air from the surrounding moves towards the flame to replace the hot air. This air also gets hot and rises. This process continues and the mode of heat transfer occurring in this manner is known as convection. Therefore, convection is the mode of heat transfer to the hand at P . On the other hand, heat transfer by radiation occurs to the hand in the position T .

E M B I B E

NCERT Exemplar Science - Class 7>Chapter 4 - Heat>SHORT ANSWER QUESTIONS>Q 14

EASY

7th CBSE

IMPORTANT

Earn 100

For setting curd, a small amount of curd is added to warm milk. The microbes present in the curd help in setting if the temperature of the mixture remains approximately between $35 ° C$ to $40 ° C$ . At places, where room temperature remains much below the range, the setting of curd becomes difficult. Suggest a way to set curd in such a situation.

Important Questions on Heat

EASY

7th CBSE

IMPORTANT

NCERT Exemplar Science - Class 7>Chapter 4 - Heat>SHORT ANSWER QUESTIONS>Q 15

You may have noticed that a few sharp jerks are given to the clinical thermometer before using it. Why is it done so?

EASY

7th CBSE

IMPORTANT

NCERT Exemplar Science - Class 7>Chapter 4 - Heat>SHORT ANSWER QUESTIONS>Q 16

Why is it advised not to hold the thermometer by its bulb while reading it?

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7th CBSE

IMPORTANT

NCERT Exemplar Science - Class 7>Chapter 4 - Heat>SHORT ANSWER QUESTIONS>Q 17

At a campsite there are tents of two shades - one made with black fabric and the other with white fabric. Which one will you prefer for resting on a hot summer afternoon? Give reasons for your choice. Would you like to prefer the same tent during winter?

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7th CBSE

IMPORTANT

NCERT Exemplar Science - Class 7>Chapter 4 - Heat>SHORT ANSWER QUESTIONS>Q 18

While constructing a house in a coastal area, in which direction should the windows preferably face and why?

EASY

7th CBSE

IMPORTANT

NCERT Exemplar Science - Class 7>Chapter 4 - Heat>SHORT ANSWER QUESTIONS>Q 19

Observe the picture given below. Water is being boiled in a pan of wide base.

Question Image

Which position $P$ or $T$ will feel warmer?

MEDIUM

7th CBSE

IMPORTANT

NCERT Exemplar Science - Class 7>Chapter 4 - Heat>SHORT ANSWER QUESTIONS>Q 19

Observe the picture given below. Water is being boiled in a pan of wide base.

Question Image

Fill up the boxes $P$ and $T$ to indicate the mode of flow of heat to the hand.

EASY

7th CBSE

IMPORTANT

NCERT Exemplar Science - Class 7>Chapter 4 - Heat>SHORT ANSWER QUESTIONS>Q 20

Look at figure given below.

Question Image

The length of wire $P Q$ in case of $A$ is equal to the diameter of the semicircle formed by the wire $C D E$ , in case $B$ . One pin is attached to each wire with the help of wax as shown in the figure. Which pin will fall first? Explain.

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