Written as per the syllabus prescribed by the Maharashtra State Bureau of Textbook Production and Curriculum Research, Pune. STD. VII.

Transcription

1 Written as per the syllabus prescribed by the Maharashtra State Bureau of Textbook Production and Curriculum Research, Pune. STD. VII Geography Printed at: Repro India Ltd., Mumbai Target Publications Pvt. Ltd. No part of this book may be reproduced or transmitted in any form or by any means, C.D. ROM/Audio Video Cassettes or electronic, mechanical including photocopying; recording or by any information storage and retrieval system without permission in writing from the Publisher. P.O. No _11650_JUP

2 PREFACE Our Std. VII Geography book comes equipped with Summaries, Maps and Illustrations, Formative and Summative Questions and Answers and of course Assessment Tests. The goal of this book is to simplify the Text Book and break it into smaller chunks so as to make it easier for the students to comprehend the subject. Every chapter in the book begins with a topic wise concise Summary that gives the readers a snapshot of the chapter. It further covers the Summative Section which includes Questions and Answers based upon the chapters and ensures that no point in the chapter is left uncovered. The section that follows consists of Formative Assessment. In this segment, we've answered as many Questions as we could and deemed necessary. To be judicious towards the exercise, we've left a few Questions unanswered and have expected the students to answer them on their own. However, this was done either based on the nature of the questions or to prod the students to dig deeper into the given topics. At the end of every chapter, we've included an Assessment Test. This test gives students a chance to test their knowledge based on what they've learned so far. We hope this book turns out to be more than a guiding angel for the students of Std. VII. The journey to create a complete book is strewn with triumphs, failures and near misses. If you think we ve nearly missed something or want to applaud us for our triumphs, we d love to hear from you. Please write to us at: mail@targetpublications.org A book affects eternity; one can never tell where its influence stops. From, Publisher Best of luck to all the aspirants! Contents No. Topic Name Page No. 1. How Seasons Occur Part The Sun, the and the Earth 4 3. Tides Air Pressure Winds Natural Regions Soils How Seasons Occur Part Agriculture Human Settlements Contour Maps and Landforms 107 Note: Textual Questions are represented by * mark.

3 1. How Seasons Occur Part 1 Chapter 1: How Seasons Occur Part I Let s Revise 1. The earth s rotation about its own axis is responsible for the occurrence of day and night on earth. 2. The earth rotates from west to east and takes 24 hours to complete one rotation around itself. 3. The period of time that the earth takes to complete one rotation is called as a day. 4. We experience different stages like sunrise, midday, sunset as well as daytime and nighttime during a day. 5. The duration of the daytime and nighttime is different on different days. 6. The position of the sunrise and the sunset also changes every day. Summative Evaluation Fill in the blanks by choosing the correct alternative from the options given 1. The earth s... enables us to measure time in terms of days. (rotation, surface, mass, distance) 2. We experience different stages like sunrise, midday, sunset as well as daytime and nighttime during a single... (year, day, month, hour) Answers: 1. rotation 2. day 1. It takes 24 hours for the earth to rotate around itself. Ans: Right. 2. The earth rotates from east to west. Ans: Wrong. The earth rotates from west to east. 3. The position of the sunrise and sunset are constant for the whole year. Ans: Wrong. The position of the sunrise and sunset keeps on changing everyday during the course of the year. Formative Evaluation Right or Wrong? If Wrong, write the correct sentence. Let s recall. (Textbook page no. 01) 1. How do day and night occur on the earth? Ans: i. Day and night occur due to the earth s rotation about its own axis. ii. While rotating, the part of the earth which faces the sun receives sunlight and hence, it is said to be day on this part of the earth. 1

4 Std. VII: Geography iii. Whereas, the other part which is away from the sun receives no light. Hence, it is dark and it is said to be night on this part. 2. What term is used to describe the orbital motion of the earth around the sun? How long does the earth take to do so? Ans: i. The orbital motion of the earth around the sun is called as the revolution of the earth. ii. Thetimetakenbyearthtocompleteonerevolutionaroundthesunisone year i.e. 365 days and 6 hours. Note: Generally only 365 days are called as one year and the 6 hours are ignored for convenience. These 6 hours are added every year, over a span of four years to make a day. This day is included in the month of February every fourth year and the year is known as leap year. 3. In which hemispheres is our country located? Ans: Our country, India, is located in the northern and eastern hemispheres of the earth. 4. Why don t the sun s rays fall perpendicular at all the places on the earth? Ans: i. The sun s rays travel in straight line and are parallel to each other. ii. However, the earth is spherical in shape. Due to this, the sun s rays are perpendicular in parts of earth near the equator and start slanting as we go further away from the equator towards the north and the south poles. Hence, the sun s rays are not perpendicular at all the places on the earth. Can you tell? (Textbook page no. 01) Note the timings of sunrise and sunset in your area, for the following period by direct observation, or using calendars, newspapers or the Internet. A specimen table has been given below. Record the entries for the month of June, find the answers to the following questions and discuss them. Date Sunrise Sunset 19 th June 20 th June 21 st June 22 nd June 23 rd June 24 th June 25 th June 26 th June 27 th June 28 th June Duration Day Night Source of Information 1. Among the records in the table which is the longest day? (Students are expected to answer the above question based on their observations.) 2. What difference do you notice in the duration of the nights day by day? Ans: The duration of the nights decreases slightly for first few days, remains stable for the next few days and then starts increasing. 3. Guess the reason behind it. Ans: The length of the day and night are not equal on all the days because of the earth s inclined axis and its revolution around the sun. 4. How did you find out the duration of the night? Ans: The time between the sunset and the following sunrise was recorded as the duration of the night or the nighttime. 2 2

5 5. Which two dates had days and nights of the same duration? (Students are expected to answer the above question based on their observations.) Chapter 1: How Seasons Occur Part 1 6. With the help of the table, you saw how the duration of the day and night changes. Do you think such a change occurs everywhere on the earth? Ans: The change in the duration of the day and night occurs on all places of the earth. However, it is almost stable on the equator. 7. Use the above format to record the duration of daytime from the 19 th to 28 th of every month from September to December. (Students are expected to note down the duration of the daytime for the specified days of the month on their own.) Try this. (Textbook page no. 02) Paste a large white paper on one side of the table. Place a torch in front of the table in such a way that it wouldn t move. Stand a rod or a candle between the white paper and the torch as shown in figure 1.1 of your textbook. Direct the light beam of the torch in such a way that the shadow of the rod/ candle falls on the paper. Mark the position of the shadow on the paper. Move the table along with the rod/ candle from one side to the other slowly. Observe and mark the position of the shadow that falls on the paper. Note the change in the location of the shadow. (Students are expected to attempt the above activity on their own.) Observation: After performing the activity, it can be observed that as the table, along with the rod/candle, is moved from one side to the other, the location of the shadow on the wall shifts in the opposite direction. Try this. (Textbook page no. 02) (For teachers: This activity is to be conducted throughout the year. Start this within eight days after the school reopens. Continue it till the end of December. Make observations once in a week at the time of sunrise or sunset as per your convenience) Take a thick stick of about 1.5 to 1.7 m long. Keeping some distance, fix the stick near a wall that receives sunlight at the time of sunrise or sunset throughout the year. (Remember that the stick has to be fixed at this spot for a period of about one year.) 1. After the observation, mark the position of the shadow for that date. 2. If the position of the shadow changes, measure and note the distance between the earlier and the changed position. 3. During the period of this activity, observe the place of sunrise and the sunset on the horizon as well. (Students are expected to attempt the above activity on their own with the help of their respective teachers.) 4. Study the duration of daytime and nighttime on the basis of observations from the table for the month of September. 5. What was the direction of the shadow of the stick in the month of September? 6. On which day was the duration of the day and the night the same? (Students must answer the questions 4, 5 and 6 after performing this activity in the month of September) Think about it. (Textbook page no. 02) If the position of the shadow on the wall moves towards the north, in which direction does the location of sunrise or sunset appear to shift? Ans: If the position of the shadow on the wall moves towards the north, the location of the sunrise or sunset will appear to shift towards the south direction in each case. 3

6 F³ellee meelejeer: Fefleneme Je veeieefjkeàmeem$e 2. The Sun, the and the Earth Let s Revise The moon s motions 1. The revolution, i.e. the orbital motion, around the earth and rotation i.e. the axial motion, about its own axis are the two motions of the. 2. The time taken by moon for one revolution around the earth is the same as the time taken by it for one rotation about itself. Hence, we constantly see only one side of the moon. 3. The moon rotates around itself and revolves around the earth which itself revolves around the sun. Hence the moon indirectly revolves around the sun. The moon s positions 1. revolves around the Earth in an elliptical orbit. Hence the distance between the earth and the moon varies. 2. When the moon is closest to the Earth, it is said to be in perigee and when it is farthest from the Earth, it is said to be in apogee. 3. Phases of the moon are visible from earth due to the sunlight reflected from the moon. 4. The moon waxes from the new moon day to the full moon day and wanes from the full moon day to the new moon day. 5. Also the moon s revolutionary orbit makes an angle of 5 with that of the earth. Thus, the moon intersects the earth s orbit twice during one revolution. The relative positions of the sun, the moon and the earth Sun New Day 0 Waning (Quarter day) 90 Waning (Quarter day) Angles made by the earth moon sun 1. On a full moon day, the is on the opposite side of the sun while revolving around the earth. 2. Similarly, on a new moon day, the moon is between the earth and the sun. 3. On the first and the third quarter days, the sun, the earth and the moon make relative angle of Full Day

7 Chapter 2: The Sun, the and the Earth Eclipses 1. An eclipse is an astronomical phenomenon occurring with respect to the sun, the moon and the earth. 2. Eclipses occur only on new moon days or full moon days, but not on every one of them. 3. On certain new moon days or full moon days, the moon, the earth and the sun fall in one line and are also in the same plane. This is when eclipses occur. 4. Thus, on a new moon day, the earth, the moon and the sun make an angle of 0 with each other. Whereas, on a full moon day this angle is Eclipses may be solar or lunar. Solar eclipse Solar eclipse occurs when the shadow of the moon falls on the earth. The conditions for the occurrence of a solar eclipse are as follows; 1. It must be a new moon day and hence, the moon is between the sun and the earth. 2. All three of them fall in the same line. 3. All three of them are in the same plane. Types of solar eclipses 1. Total solar eclipse: In the area s of the earth where moon s dark shadow (the central portion of the shadow) falls, the sun becomes completely invisible. Such an area experiences a total solar eclipse. The maximum duration of a total solar eclipse is 7 minutes and 20 seconds (440 seconds). 2. Partial solar eclipse: In the area s of the earth where moon s lighter shadow (the peripheral portion of the shadow) falls, the sun appears partially invisible. Such an area experiences a partial solar eclipse. 3. Annular solar eclipse: When the moon is in the apogee position, its shadow is cast in space and does not reach the earth. We can see only an illuminated edge of the sun in the form of a ring. This is called as annular solar eclipse. Remember: While observing a solar eclipse, the intense light of the sun can harm the eyes. So we must wear black glasses or special goggles made for this purpose. Lunar eclipse Lunar eclipse occurs when the moon enters the earth s shadow while revolving around it. The conditions which should be satisfied are as follows; 1. It must be a full moon day and hence, the earth is between the sun and the moon. 2. All three of them fall in the same line. 3. All three of them are in the same plane. Types of lunar eclipses 1. Total lunar eclipse: On a full moon day, when the moon passes through the shadow of the earth and is completely hidden by it, we see a total lunar eclipse. The maximum duration of a total lunar eclipse is 107 minutes. 2. Partial lunar eclipse: If the moon is partially hidden due to the shadow of the earth we see a partial lunar eclipse. Occultation It occurs with reference to the moon. While revolving around the earth, the moon obscures a star or a planet and that celestial body appears to be hidden behind the moon. This is called as occultation. During a total or annular solar eclipse, the sun appears to be hidden behind the moon. Hence, this too is a kind of occultation. 5

8 Std. VII: Geography Transit It occurs with reference to the sun. When an inner planet (i.e. a planet whose orbit lies between the sun and the orbit of earth) like Mercury or Venus comes in between the line of the earth and the sun, a transit occurs. During transit, a small dot appears to move across the sun s disc. It is a type of solar eclipse. Summative Evaluation Select the correct option *1. Apogee position of the moon a. b. c. *2. Solar eclipse a. b. c. 3. Lunar eclipse a. b. c. *4. The shape of sun disc at the time of an annular solar eclipse a. b. c. Ans: (1 a) (2 b) (3 c) (4 b) 1. The position of the moon when it is closest to the earth. 2. The position of the moon when it is farthest from the earth. 3. The angle formed between the moon, the earth and the sun on the first and the third quarter days. 4. The angle formed between the revolutionary orbits of the moon and that of the earth. Ans: 1. Perigee 2. Apogee Answer in one word

9 Chapter 2: The Sun, the and the Earth Rewrite the correct sentences 1. The revolves around the Sun. Ans: The revolves around the Earth which itself revolves around the sun. Thus, the moon indirectly revolves around the sun. 2. On a full moon day, the moon, the sun and the earth are positioned in this sequence. Ans: On a full moon day, the sun, the earth and the moon are positioned in this sequence. 3. The revolutionary orbits of the Earth and the are in the same plane. Ans: The revolutionary orbits of the Earth and the are not in the same plane but they make an angle of 5 with each other. 4. In one revolution of the, its orbit intersects the Earth s orbit only once. Ans: In one revolution of the, its orbit intersects the Earth s orbit twice. 5. An annular solar eclipse occurs when the moon is in the perigee position. Ans: An annular solar eclipse occurs when the moon is in the apogee position. 6. It is alright to observe a solar eclipse without protecting the eyes. Ans: While viewing a solar eclipse it is necessary to use dark glasses or goggles made especially for that purpose, else it can harm the eyes. Answer in one sentence 1. What types of solar eclipses occur in the perigee position of the moon? Ans: Total and partial solar eclipses occur in the perigee position of the moon. 2. Why do the illuminated phases of moon become visible? Ans: The illuminated phases of moon become visible due to the sunlight reflected from the moon. 3. What is the position of the moon with respect to sun, on full moon day and new moon day? Ans: On a full moon day, the moon is on the opposite side as that of the sun, while on the new moon day, it is between the sun and the earth. Complete the flow chart Eclipse Lunar eclipse i. ii. Partial lunar eclipse Total solar eclipse iii. iv Ans: i. Solar eclipse ii. Total lunar eclipse iii. Partial solar eclipse iv. Annular solar eclipse 7

10 Std. VII: Geography Complete the following table *Complete the following table: Details Lunar Eclipse Solar Eclipse Phase of the moon i.... New moon day Sequence Earth Sun ii.... Type of eclipse iii.... iv.... Maximum duration of total eclipse 107 minutes v.... Ans: i. Full moon day. ii. Sun Earth iii. Total lunar eclipse, Partial lunar eclipse iv. Total solar eclipse, partial solar eclipse and annular solar eclipse v. 7 minutes and 20 seconds (440 seconds) Draw and label the diagrams 1. s positions Ans: Apogee Perigee Earth s positions *2. Total and partial solar eclipse Ans: Earth Partial solar eclipse Earth s orbit Total solar eclipse Sun 3. Annular solar eclipse Ans: Earth Total and partial solar eclipse Annular solar eclipse Sun Partial solar eclipse 8 8 Annular and partial solar eclipse