Detailed explanations in West Bengal Board Class 7 Geography Book Solutions Chapter 1 Earth’s Revolution offer valuable context and analysis.
WBBSE Class 7 Geography Chapter 1 Question Answer – Earth’s Revolution
Can you say?
Question 1.
How many rotations are completed in the course of one revolution?
Answer:
The Earth rotates 365 times to revolve once around the Sun.
Question 2.
How many minutes are there in 24 hours or 1 day?
Answer:
There are 1440 minutes in 24 hours or 1 day.
That’s easy
Now write down correctly.
year – leap year
2004 – yes
2000 – yes
2012 – yes
1900 – no
2013 – no
2100 – no
Have you thought (page no.-9)
When do you think we get more heat during day time?
All the time of sunrise
At noon when the sun is overhead
During sunset
At night after sunset
Answer:
At noon when the sun is overhead
Let’s get down to work (page no.-11)
Month – Direction from which the sun rises
March – middle of Eastern sky
May-June – kloser to North
September – middle of Eastern sky
November – closer to South.
The shadow in a Sundial : (Page no. 13)
Question 1.
On which day the length of the shadow is smallest?
Answer:
The length of the shadow is smalest on 21 st June.
Question 2.
On which day the length of shadow is longest.
Answer:
The length of shadow is longest on 22nd December at 12 O’clock noon.
Brainware (Page no. 16)
Think and solve :
What will happen if the axis of the Earth is perpendicular to the Earth’s orbital plane?
Answer:
The days and nights would be equal and there would be no season change.
If the axis of the Earth is in the same plane with its orbit?
Answer:
The days and nights would be equal and there would be no season change.
Where days and nights are equal?
Answer:
Days and nights are equal in the equatorial region.
What is the local time of sunrise in Tokyo, Kolkata and Sidney on 21st March?
Answer:
On 21 st March the sun rises at 5 p.m. in Tokyo Kolkata and Sidney.
What is local time of sunrise on 4th July, 25th January and 20th September at any place on the equator?
Answer:
On 4th July, 25th January and 20th September the Sun rises at the same time at any place of equator.
At what local time does the sun set in New York, Delhi and Cairo on 23rd September?
Answer:
The sun set in New York, Delhi and Cairo at 5 pm. on 23rd December.
Reverse Seasons in North and Southern Hemisphere (Page no. 17)
Answer:
21 st June-(i) hibiscous, mango, black berry, jackfruit,
(ii) the shortest night.
(iii) Starting of Winter.
23rd September- (i) The day and the night are equal.
(ii) equal day-night.
22nd December-
(i) The smallest night.
(ii) Marrygold, Dahlia, Apple, Orange
(iii) Starting of Summer.
CrossWord :
Across
1. The eighth planet
5. The shape of the earth’s orbit
6. The dramatic play of light in the night sky near the poles.
7. 23 1/2° N = Tropic of ………..
Up-Down
2. The position when the earth is farthest away from the Sun on its orbit.
3. Equal days and equal nights.
4. Our galaxy.
Do it yourself
In which season do we have a clear sky on most of the days?
Answer:
We have a clear sky in winte.
Name the season in which the earth is parched?
Answer:
The earth is parched in Summer.
Name the season in which ponds are full of water.
Answer:
Ponds are full of water in Rainy season.
Name the season in which floods are likely.
Answer:
Floods are possible in Rainy season.
Name the season in which you can actually fish in shallows and canals.
Answer:
Fishes are collected from shallows and canals in winter and spring.
In which season does the location of sunrise shift the most southward in the sky.
Answer:
The sun rises from extreme southward of the sky in winter.
In which season is the shadaw at 12 noon found to be the longest compared to the rest of the year?
Answer:
The shadow becomes longest at 12 noon in winter.
What is name of the season when you hear the cuckoo calling?
Answer:
Cuckoo calls in spring.
In which season is the day longest in the Northern hemisphere?
Answer:
Day is longer in northern hemisphere in summer.
Does the southern hemisphere feel warm or cold on 25th December?
Answer:
On 25th December southern hemisphere experiences hot.
Why the scientists visit Antarctica in December.
Answer:
Antarctica lies in south hemisphere. The south hemisphere experiences summer in December. For Dakshinayan the sunrays fall perpendicularly on Southern hemisphare at that time and thus the days are longer and nights are shorter. Then the summer begins. The ice starts melting in Antarctica. The weather becomes little pleasant. So the scientists visit Antarctica in December.
When do we come closer to the Sun July or January?
Answer:
We come closer to the sun in January.
Class 7 Geography Chapter 1 Question Answer West Bengal Board – Earth’s Revolution
Multiple Choice Questions & Answers : (1 mark for each question)
Question 1.
At the time of creation the earth was thrown away from –
i) a unknown star
ii) universe
iii) the sun
iv) the moon
Answer:
iii) the sun
Question 2.
The sun is revolving around the centre of our galaxy-
i) alone
ii) with all its planets
iii) with all its planets and their satellites
iv) with earth
Answer:
iii) with all its planets and their satellites
Question 3.
The speed of earth’s annual motion or revolution is 30km per –
i) second
ii) minute
iii) hour
iv) day
Answer:
i) second
Question 4.
On 4th July the distance between the Sun and the Earth is-
i) mimimum
ii) maximum
iii) medium
Answer:
ii) maximum.
Question 5.
The time taken by the earth to move round the sun-
i) 365 days
ii) 366 days
iii) 366 days 5 hours
iv) 365 days 5 hrs 48m 46 sec
Answer:
iv) 365 days 5 hrs 48 m 46 sec
Question 6.
Oblique rays of the Sun cover a –
i) larger area
ii) smaller area
iii) i true, ii false
iv) i false, ii true
Answer:
iii) i true, ii false
Question 7.
When the Northern hemisphere is inclined towards the sun-
i) the days are longer
ii) temperature increases
iii) nights are shorter
iv) All are true
Answer:
iv) All are true
Question 8.
When the Southern hemisphere is inclined towards the sun-
i) summer prevails
ii) winter prevails
iii) spring prevails
iv) autumn prevails
Answer:
i) summer prevails
Question 9.
Sunrays fall vertically on the equator-
i) six months
ii) throughout the year
iii) three months
iv) nine months
Answer:
ii) throughout the year
Question 10.
In the period between 21 st June and 22 n December the sun apparently shifts
i) northward
ii) southward
iii) i true ii false
iv) i false ii true
Answer:
iv) i false ii true
Question 11.
On 21 st June Sun’s rays fall directly on-
i) Tropic of Capricorn
ii) Antarctic circle
iii) Tropic of Cancer
iv) none of these
Answer:
iii) Tropic of Cancer
Question 12.
In Northern Norway the Sun is clearly seen in the sky even at midnight from-
i) May to July
ii) January to March
iii) March to May
iv) July to September
Answer:
i) May to July
Question 13.
The Northern and Southern polar regions experience continuous days and nights for-
i) three months
ii) six months
iii) nine months
iv) one month
Answer:
ii) six months
Question 14.
In North Polar region the sun never sets below the horizon from-
i) 21st March to 21st June
ii) 21st January to 21st April
iii) 21st April to 21st July
iv) 21st March to 21st June
Answer:
iv) 21 st March to 21 st June
State whether True or False : (1 mark for each question)
1. Any object on the Earth is attracted to its centre.
Answer:
True
2. The Sun is 10 lakh times bigger than the earth.
Answer:
False
3. The moon revolves around the Earth.
Answer:
True
4. The Earth revolces around its own axis.
Answer:
True
5. The speed of annual motion or revolution of Earth is 10 km per second.
Answer:
False
6. Kepler introduced four laws.
Answer:
False
7. Artisicial satellites are launched into their orbits at escape velocity.
Answer:
True
8. On 4th July the distance between the Sun and the Earth is least.
Answer:
False
9. A year is calculated on the basis of one complete”revolution of the earth.
Answer:
True
10. North and south two polar region experience day and night with a span of six months.
Answer:
True.
11. On two polar belts the sun rays fall perpendicularly through out the year.
Answer:
False.
12. 22nd June the Sun rays fall directly on equator.
Answer:
False.
13. The Earth revolves round the Sun in an elliptical orbit.
Answer:
True.
14. From January to July the Earth goes far away the Sun.
Answer:
True.
Fill in the blanks : (1 mark for each question)
1. The attraction force of the Earths is called ______.
Answer:
Gravitational force.
2. The Earth is ______ times smaller than the Sun.
Answer:
13 Lakhs.
3. The rate of revolution of the Earth is ______ per second.
Answer:
30 km.
4. Earth’s Aphelion occurs on _____.
Answer:
4th July.
5. Earth’s perihalion occurs on ______.
Answer:
3rd January.
6. The year consisting 366 days is called ______.
Answer:
Leap year.
7. On 21st June the Sun rays fall perpendiculary on ______ and 22 and December. The Sun rays fall perpendicularly on ______.
Answer:
Tropic of cancer, Tropic of capricon.
8. The Sun’s apparent migration is called ______.
Answer :
Rabi Marg.
9. The Earth is ______ inclined on its orbit.
Answer:
66 1/2°,
10. The upper end of the Earth is called ______ and lower end is called ______.
Answer:
North pole, South pole.
11. The Escape velocity is ______ per second.
Answer:
11.2 km per second.
12. The-mon revolves round the Earth in ______ days:
Answer:
28 .
13. The period between 22nd December to 21 st June the Sun apparent motion towerds the north is called ______.
Answer:
Northern Solstice.
14. The span of this day longest in Northern hemisphere on ______.
Answer:
21 st June.
15. ______ Land is known as the Jand of Midnight Sun.
Answer:
Hammerfest port.
Match the column A with columo B.
| Column A | Column B |
| a) On 21st March Sun’s rays fall | i) is not seen in the Arctic region |
| b) On 21st June Sun’s rays fall | ii) gets egual day and night |
| c) Equinox means | iii) is 21 st June |
| d) From September to January the Sun | iv) in 365 days |
| e) In Northern Hemisphere 2 sst March | v) directly on the equator |
| f) Longest day in Southern Hemisphere | vi) as a leap year |
| g) Shortest day in Southern Hemisphere | vii) directly on the Tropic of Cancer |
| h) The Earth revolves round the sun | viii) on 4th July is maximum |
| i) $\mathbf{2 0 1 2}$ is considersd | ix) equal day and night |
| j) The distance between Sun and the Earth | x) 22 nd December |
Answer:
a) On 2 kst March Sun’s rays fall directly on the equator.
b) On 2 lst June Sun’s rays fall directly on the Tropic of Cancer.
c) Equinox means equal day and night.
d) From September to January the Sun is not seen in the Arctic region.
e) In Northern Hemisphere 21 st March gets egual day and night.
f) Longest day in Southern Hemisphere 22nd December.
g) Shortest day in Southern Hemisphere is 21 st June.
h) The Earth revolves round the sun in 365 days.
i) 2012 is considersd as a leap year.
j) The distance between Sun and the Earth on 4th July is maximum.
Very Short Questions & Answers : (1 mark for each question)
Question 1.
What is the name of the milky way the Earth belongs to?
Answer:
The Earth belongs to the milky way named Akash Ganga.
Question 2.
What is the axis of the Earth.
Answer:
The imaginery line around which the Earth rotates is called the axis of the Earth.
Question 3.
What is ‘Escape velocity’?
Answer:
At which speed moving object can avoid the gravitational force of the Earth is called Eacape velocity.
Question 4.
What is the shape of the Earth?
Answer:
The shape of the Earth is spherical.
Question 5.
What is Luner month?
Answer:
The moon the satellite of Earth takes 28 days to revolve the Earth. This is called ‘luner month’.
Question 6.
What is equinox?
Answer:
The equinox means the equal length of day and night.
Question 7.
On which day the day and night is equal through out the world?
Answer:
On 21 st March and 23rd September the day and night are equal throught out the world?
Question 8.
Which day is called vernal equinox?
Answer:
2 ist March is called vernal equinox.
Question 9.
Which day is known as Autumnal equinox?
Answer:
23rd September is known as Autumnal equinox?
Question 10.
What is called the land of Midnight Sun?
Answer:
Hammerfest port in Northern Norway is called the land of Midnight Sun.
Question 11.
Who stated first about the actual motion of the planet?
Answer:
Scientist Kepler stated first about the actual motion of the planet.
Question 12.
What is the shape of the orbit of the Earth?
Answer:
The orbit of the Earth is elliptical.
Question 13.
How many season are there in a year?
Answer:
There are six seasons in a year.
Question 14.
from where we can sea the Aurora Borialis and Aurora Austratis?
Answer:
We can see a Aurora Borialis from Narth pole and Aurora Australis from south pole.
Question 15.
Name two seasonal flowers of Autumn?
Answer:
Two seasonal flowers of Autumn are Seuli and cas.
Question 16.
Why is the distance between the Sun and the Eakth is not always same?
Answer:
The distances between the Sun and the Earth is not always same as the Sun stays at one focus of the eliptical orbit.
Question 17.
Or which days the distance between the sun and the Earth is lowest?
Answer:
The distance between the Sun and the Earth is lowest on 3rd January.
Question 18.
What is solar year?
Answer:
The Earth takes 365 days to revolve rotnd the Sum. This is called Solar year.
Question 19.
On which days the Sun rays falls perpendicuharly on the Equator?
Answer:
On 21st June and 22nd December the Sun rays fall perpendicularly on the Equator?
Question 20.
On which day Summer solstice occurs?
Answer:
Summer solstice occurs on 21 st June.
Question 21.
On which day Winter Solstice occurs?
Answer:
Winter Solstice occurs on 22nd December.
Question 22.
What is the value of Arctic Circle?
Answer:
The value of Arctic Circle is 66 1/2° North.
Question 23.
Which day is called vernal equinox?
Answer:
21 st March is called vernal equinox.
Question 24.
Which day is called Autumnal eqinox?
Answer:
23 td September is called Autumnal eqinox.
Question 25.
What is called the apparent soutly ward nigration of the Sun.
Answer:
The apparent south ward migration of the S(u) is called Dakshinayan.
Question 26.
What is the value of the Tropic of capricon.
Answer:
The value of the Tropic of capricon is 23 1/2° South.
Question 27.
Which is the longest day and shortest night in the northern hemisphere?
Answer:
21 st June is the longest day and shortest night in the northern hemisphere.
Question 28.
How much is the East inclined on its orbit?
Answer:
66 1/2°
Question 29.
In which hemisphere our country is situated?
Answer:
Our country is situated in Northern hemisphere.
Question 30.
What is the rate of revolution of Earth per second?
Answer:
the rate of revolution of Earth per second is 30 km.
Question 31.
Who thought first about leap year?
Answer:
Egyptians thought. first about leap year.
Question 32.
What is the source of life on Earth?
Answer:
The Sun is the source of life on Earth.
Question 33.
Which season does the Southern hemisphere enjoy where there is Autumn in Northern hemisphere?
Answer:
Spring.
Short Questions & Answers : (2 marks for each question)
Question 1.
What is rotation?
Answer:
The Earth rotates around its own axis like a top from west to east. It takes 24 hours for one rotation. This is called the rotation of the Earth. Day and night cause due to the rotation of the Earth.
Question 2.
How many motions does the Earth have? What are they?
Answer:
The Earth has two types, of motion. They are rotation and revolution.
Question 3.
What is revolution of Earth? Give the result of its :
Answer:
The Earth revolved around the Sun on its elliptical orbit spinning around its owm exis a like a top. This is called revolution.
Revolution causes the season change and increasing and decreasing of the length of the day.
Question 4.
What is Aphelion and Perihelion?
Answer:
Aphelion is the point of the Eart’s orbit that is farthest away from the Sun. The Perihelion is the point of the Earth’s orbit that is nearest to the Sun.
Question 5.
What is Autummal eqinox?
Answer:
On 23rd September the Sun rays fall directly on Equator. For this reason the d.ys and night equal through out the Earth. The northern hemisphere experences autumn. Thus it is called: Autumnalequinox.
Question 6.
What is summer solstice.
Answer:
On 21 st June the Sunrays fall directly of tropic of cancer: On thit day the is longest in Northern hemisphere and smallest.in Southern hènisphere. Arctic circle experience day light fir 24 hours. Antertic circle remain in darkness for 24 hours. It is called Summer solstice:
Question 7.
What is Rabi Marg of the apparent annual motion of Sun?
Answer:
The Earth is 66 1/2° inclined on its plane of orbits, So the Sun ray falls sometines perpendicularly, sometimes inclined or Equator. Tropic of cancer and Trcpic of capricon. So the – Sun seems to migrate from Equator to Tropic of cancer to the month and them to Tropic of Capricon to the Sotth: This is called the Rabi Marg and the apperent annual motion of Sun.
Question 8.
What is Uttarayan and Dakshinyam.
Answer:
On 22ud.Décember the Sunrays fall directly on Tropic of capricon and then it gradually becomes inclined towards the north pole. Thus it seems that Sun-migrates towards northand this is called Uttarayan. From 21st June to 22 nd Đecember the apparent migration of the Sun towards Soutli is called. Dakshinayan.
Question 9.
What is Aurora Borialis and Aurora Australis?
Answer:
In the north polar-region -and in the south polar region, when there are day and night -with a spati of six months a tight like a rainbow seen or the sky: It is the result of the colfision of sun – ray and the ionised gas present in atmosphere. In north pole it is called Aurora Borialis and in south pole it is called Aurora Australis.
Question 10.
What do you know about Aphelion and Perihelion.
Answer:
The Sun ties at the focus point of the ellipticat orbit of the Earth. So the distance between the Earth and the Sun is not the same at the time of revolution. On 4th July the distance between the Sun, and the Earth is maximum almost 15 crore 20 Lah km. This is called Aphelion On the other hand the distajce between the Sun and the Earth is towest on 3rd January almost 14 crorer 70 lakh km. This is called Perihelion. For this reason the Sun look bigger in winter and smaller in summer.
Long Questions & Answers : (3 marks for each question)
Question 1.
What is leap year?
or,
Why does the month of February not consist 29 days all time?
Answer:
The Earth takes 365 days 5 hours 48 minutes 46 second to complete one revolution but we take 365 days for a year to make the calculation easy. So the extra 5 hours 48 minutes and 46 second is considered as a day after 4 years and is added with the days of February every fourth years. So every fourth years the month of February consists 28+1=29 days the year cortsists 366 days. Thiş year is called leap year. The year. which is totally devisible by four and there is no remainder, is called leap year. But the century years (such as 1900.2000 , should be divided by 400 to calculate correctly.
Question 2.
Write the important factors at the time of revolving of the earth around the Sun.
Answer:
The important factors are-
(i) Spinning like a top on its own axis the Earth completes one revolution around the Sun in 365 days.
(ii) The Earth’s axis is always tilted.
(iii) The shape of the Earth’s orbit is elliptical.
(iv) The Earth’s axis is 66 1/2 inctined or its orbit and the plane of orbit is 23 1/2° inclined on the equarorialplane.
(v) The Sun ties at the focus of the Earth elliptical orbit and for this reason the distance between the Sun and the Earth is not always the same. The rate of the revolution changes due to this fact. For the changes of the distance the sun fooks sometimes biggers and sometimes smaller.
(iv) The Earth revolves the Sun from East to West.
Question 3.
What do you Undurstand by the turn ‘season change’? How do the advent of the different seasons occur in the two hemisphere?
Answer:
The temperature of the different places and differnt times verious for the different inclination of the Sun rays and the increase and decrease of this length of the day. Based on these difference the whole year in divided into some parts. Each of the part is considered as a season. The changing of the season in a circleing way is called season change. Four season dominate in the Earth. They are summer autumn, winter and spring.
a) The spring in Northern hemispher: At time of rotation of its own axis they cones such a point from where the sunrays fall vertically on the equator. Then the two pole of the Earth lie at the same distance from the sun. Thy day and night are equal at all the places of the Earth. The day is with the span of 12 hours and night is also of 12 hours. This is known as autumnal equinox. The weather is pleasant as the day and night are equal. At that period the northern hemisphere enjoyes spring and autumn prevails in Southern hemisphere.
b) Summer in Northern hemisphere: After 21 st March the Northern hemisphere gradually comes towards the sun. The sun reaches the end point of Uttarayan. On that day the sun rays fall vertically on the equator. So the northern hemisphere experiences the day more than 12 hours and the night less than 12 hours. For the longer days and the vertical sunrays one and half months before and after 21 st June the weather is better in northern hemisphere and the opposition condition is found in southern hemisphere. 21 st June is called the Summer Solstice.
c) Autumn is Northern hemisphere : After 21 st June the southern hemispherc comes closer to the Sun the Dakshinayan of the Sun starts. On 23rd September the two poles remain at the same distance from the sun. On that day the sun rays fail on the equator. The days and nights are same through out the world. The weather remains pleasant. There is autuma in norther: hemispliere and spring in Southern hemisphere. Thus on 23rd september there is autumn in northern helmisphere and spring in southern hemisphere. 23 rd September is autumnal equinox in northern hemisphere.
d) Winter in Northern hemisphere : After 23 September the sunrays fall vertically on southern hemisphere. The sun rays fall vertically on Tropic of capricon on 22 nd December on that day the Southern hemisphere has the longest days and the smallest day. During one and half month before and after 23rd September the summer season prevails in soutiern hemisphere. This day is called salstice. In northern hemisphere has the shortest day and the longest night. So it is winter in Northern hemisphere.
Additional Questions and answers
Question 1.
Definc revolution of earth.
Answer:
Movement of the earth around the sun on a fixed path or orbit is called revolution.
Question 2.
Write the charaçteristics of revolution:
Answer:
- Annual motion of the earth around the sun is called revolution.
- The time of revolution is 365 days 6 -bours.
- The change of season takes placedue to the revolutiom of the earth.
Question 3.
What is orbit?
Answer:
Orbit. is the eclliptical path on which heavenly bodies move around the sun or planet.
Question 4.
What is – axis?
Answer:
The axis of the earth is an inganinary line joining the north pole with the south pole.
Question 5.
Why do seasons change on the earth?
Answer:
Due to change in the position of the earth around the sun.
Question 6.
What is leap year?
Answer:
Six honrs saved eyery year in revolution are added in four years. They become 24 hours or one additional day. The day is added to the month of February every four years. So every fourth year February has one more day-29 days instead of 28 days. Such a year of 366 days – is called a leap year.
Question 7.
Mehtion the natural ways by which we can measure time.
Answer:
First method- Day and night occurs within 24 hours. When the Earth rotates, – sometimes it takes us away from the Sun. But again it makes us face the Sun. In fact, the Earth rotates slowly under the Sunrays. The portion of Earth.which receives the Sun’s rays experiences day while the other half of ths Eart has night.
Second method- The Earth’s satellite, Moon, revolves around the Earth in about 27 1/2 days. This is called a Lunar month”: Although 30 days is the standard duration of the month, some months have 31 or even 28 days.
Third methot-Revolution of the Earth. The Earth revolves around the Sun in 365 days. This time is called solar year. A year is calculated on the basis of one complete revolution of the earth. So revolution is also called the Annual Motion.
Question 8.
Why do seasons occur?
Answer:
When the Northern hemisphere is inclined towards the Sun, the days become gradually longer and nights gradually shorter there. The duration of daytime thus increases. The Earth gets lieated througliout the day.As nights are shorter, the Earth does not get enough time to cool down. So femperature keeps rising. During this period the Northern hemisphere gets direct Sunrays. So temperature increases. This is summer time in Northern Hemisphere but winter time in Southern Hemisphere.
When the Southern Hemisphere’ is inclined towards the Sun, the days shorteri and nights lengthen inthe Northern Hemispliere. The Sumlight does not.persist for a longtime, so the Earth does not get heated intensely. It cools down through out the long nights. During this period the Northern Hemir spinere receives oblique Sunrays, So it gets less heated. In this period winter prevails in Northern Hémisphere but summer prevails in Southern Hemisphere.
Question 9.
What is illuminated night and dark day?
Answer:
Beyond Arctic’ and. Antarctic circles the ‘Sunrays fall obliquely through the year. – From 2.1st March to 21 st June in North Polar region the Sun never sets below the horizon: In this period this-region receives Sunlight throughout 24 hours. That means the Sun shines even at night-as per their local time. From 23rd September to 22 ind December the same thing happens in the Southern Hemisphere.
From March to June or July, many parts of Canada, Alaska, Norway, Sweden and Icéland receive sunlight even at midnight. From Hammerfest port situated in Northern Norway the Sun is clearly seen (May to July) in the sky even at midnight. So this land is called Land of the Midnight Sun.
From September to January the Sun is never seen in the Arctic region. Darkness prevarls for 24 hours. This means that the Sun is not seen in the sky ever if it is day time as per local timings. From March to June the same thing happens in the Antarctic region.