Geographic Grid: Latitudes and Longitudes         Question and Answers

Exercises

I. Short Answer Questions

Question 1.What is a geographic grid ?

Answer:The network of the latitudes and the longitudes is known as a geographical grid.

Question 2.Who devised the lines of latitude and longitude ?

Answer:Eratosthenes, the Greek philosopher, first time devised the lines of latitude and longitude.

Question 3.What are lines of latitude and longitude ?

Answer:The latitudes are the parallel circles with respect to the equator reducing in length

northwards and southwards and the poles are the points only. On the other hand

longitudes are equal in length drawn from North Pole to South Pole with their intervals

reducing towards poles.

Question 4.Mention two characteristics of lines of latitude ?

Answer:(a) The lines of latitude are parallel to the equator.

(b) The lines of latitude are drawn at an angular distance with respect to the equator.

Question 5.Name the two hemispheres of the earth made by the Equator.

Answer:Northern hemisphere and Southern hemisphere.

Question 6.Express 1° angular distance in kilometres.

Answer:As the circumference or the equator is nearly about 40,000 km.

So 1° angular distance in km. will be 40,000/360 =111 km. approximately. 

Question 7.Name the thermal zones of the earth.

Answer:The thermal zones of the earth are Tropical, Temperate and Polar zones.

Question 8.With the help of degrees, name the important lines of latitude.

Answer:

(a) Tropic of Cancer — 23 1/2°N

(b) Tropic of Capricorn — 23 1/2° S.

(c) Arctic Circle — 66 1/2° N.

(d) Antarctic Circle — 66 1/2° S

(e) North Pole — 90°N

(f) South Pole — 90°S

Question 9.Which temperature zone receives almost vertical rays of the sun and which zones receive slanting rays ?

Answer:The Tropical zone gets vertical rays of the sun, while temperate and polar zones receive slanting rays of the sun.

Question 10.Which line is known as the Prime Meridian ? State its importance.

Answer:Greenwich Meridian is called the ‘Prime Meridian’ or the 0° longitude. The time is calculated with respect to this Meridian. So it is the basic Meridian and time is written as G.M.T. (Greenwich Meridian Time) The earth takes 4 minutes for moving 1° distance.

Question 11.How can the general climate of an area be described with the help of the lines of latitudes ?

Answer:The temperature decreases northwards and southwards from the equator. The region within 23 1/2° N and 23 1/2° S will get tropical climate with ample temperature and rainfall. On the other hand the regions between 23 1/2° N – 66 1/2° N and 23 1/2° S – 66 1/2° S will get temperate climate, while the regions known as Arctic and Antarctic circles get very cold polar climate as Tundraregion. 

Question 12.Which line of longitude is used to fix the World Standard Time ? State its value in degrees.

Answer: Greenwich Meridian is used to fix the World Standard Time. Its value in degrees is 0°.This time is written as G.M.T.

Question 13. State the longitudinal value in degrees of Indian Standard Meridian.

Answer: Longitudinal value of Indian Standard Meridian is 82 1/2° E. It passes midway through India nearly along the city of Allahabad.

Question 14. What is meant by IDL ? State its importance.

Answer: IDL means the International Date Line, which is along 180° E & W. The date or day changes while crossing this line i.e. while there is Monday in the Eastern Hemisphere i.e. 0° – 180°E, there will be Sunday in the Western Hemisphere i. e. 0° – 180° W.

Question 15. What are the Great Circle Routes ? State their importance.

Answer: The Great Circle Routes follow the great circles i. e. the perimeters of the earth, which cover the shortest distances between any two places in spite of the zigzag routes along the surface of earth. These circles are beneficial for following the shortest distances between any two places and help in saving the time. i. e. the shortest routes are covered in minimum time span.

Question 16. What is a globe ? State the importance of a globe.

Answer: A globe is a man-made spherical model of the earth. A globe is very useful model to display the actual shape of the earth with its tilted axis ; The rotation and revolution of the earth can be very clearly shown by it along with the continents and oceans.

Give reasons for each of the following

Question 1.Lines of latitude carve out the heat zones of the earth.

Answer:The Temperature goes on decreasing from the equator towards the poles. So the latitudinal zones are the actual heat zones of the earth, namely tropical, temperate and polar zones.

Question 2. Lines of longitude are also called Meridians of longitude?

Answer: The word ‘meridian’ means related to noon or 12 p.m. As every longitude receives the noon time or 12 p.m. at different intervals where the sun’s rays are exactly vertical over a particular longitude. On a particular longitude the noon-time is the same from north to south ; so a longitude is also called a Meridians of longitude.

Question 3. Diametrically opposite lines of longitude and the Equator are called Great Circles.

Answer: Every longitude along with its opposite longitude makes a complete circle around the earth and another complete big circle is the equator; while the latitudes make smaller circles along with the poles to be only points. So the equator and the longitudinal lines around the earth are called the Great Circles.

Question 4.The Greenwich time is called Greenwich Mean Time.

Answer:The time of any place or country is calculated according to the 0° longitude or Greenwich meridian, the time change is of 4 minutes for every 0° longitude. So it is called Greenwich Mean Time.

Question 5. IDL deviates and goes zig-zag near some Islands in the Pacific ocean.

Answer: IDL is not a straight line, but it deviates in order to classify some scattered Islands in a particular divisions of Hemispheres, so that the day and time can be calculated according to the line, as the natural position of the Islands is haphazard.

Question 6. A globe is the most popular model of the earth.

Answer: As our earth is spherical in shape, so it can be best represented by a spherical model like a globe. A globe illustrates the position of continents and oceans, the tilted axis of the earth, its rotation, the sea and air routes etc. So a globe is a perfect model of the earth. 

Long Answer Questions

Question 1. Describe the lines of latitude, their importance and use.

Answer: The face of the earth is divided into various parallel circles with respect to the equato on both sides at different angular distances. These lines are veiy important to decide the climate and temperature range of any place or region as the temperature goes on decreasing from the equator to polewards.

Question 2. With reference to the International Date Line, state the following:

(a) It is meaning and application.

(b) The important deviations it makes and reasons for the same.

(c) Give an example of how time lost or gained is computed with reference to this line.

Answer:

(a) The time and date changes as we cross the International Date Line i.e. the

navigators or pilots have to loose one day while crossing westwards and gain one day

while crossing eastwards i.e. When one travels from Tokyo to San Francisco on

Monday, he will reach San Francisco on Sunday.

(b) The International Date Line is not a straight line but have some deviations in order to

adjust with the pattern of the landforms and some islands to decide for the time and

date of these places and regions.

(c) If we are moving from Hawaii Islands towards Shanghai on Tuesday, we will reach

there on Wednesday or Thursday probably, but if we are going eastwards from Shangai

to Hawaii islands on Tuesday. We may reach there either on Tuesday or Monday.

Question 3. Describe the lines of longitude and state their use in relation to distance and time.

Answer:

A longitude is the angular distance of a place east or we§t of the Prime Meridian or 0° longitude. The lines of longitude are the great semi-circles joining North pole and South pole and are equal in length. These are 0° – 180°E and 0° – 180°W longitudes or total 360°. As the earth takes 24 hours to make a complete rotation along its axis crossing 360° lines of longitude, so earth takes nearly 4 minutes to move one degree (1 °) longitude or 111 km length or distance. There is difference of time of one hour between 15° interval of longitudes. According to the clock-time, EGA stands for East-Gain-Add and WLS means West Lose Subtract. In other words for each 10 longitude towards east 4 minutes are to be added and towards west for each 1° longitude 4 minutes are to be subtracted.

Question 4.

Make a detailed study of finding time with the help of longitudes. Give one practical example.

Answer:

Indian Standard Time is based on 82 1/2° E longitude. So if the time in India is 12 noon, so it will be 6.30 A.M. in England or GMT. The time difference between 0° and 82 1/2° E will be 82.5 × 4 – 330 minutes or 330 ÷ 60 = 5 1/2 hours. So there is difference of 5 1/2 hours between India and England, as England lies in the west, so the time will be 5 1/2 hours less than India. 

Answer the following questions

Question 1.An important programme was to be broadcast from Mumbai at 7.30 p.m. This was heard by some Indian sailors near Ivory Coast in West Africa at 20°W longitude. What was the local time there ?

Answer:

According to the Indian Standard Time 7.30 p.m. based on 82 1/2° E. Longitude was the

time at Mumbai. The longitudinal difference between Mumbai and Ivory Coast at 20° W

is 82.5 + 20 = 102.5. So 102.5 × 4 = 410.0 minutes = 6 hours 50 minutes, i.e. the time

will be 6 hours 50 minutes less than 7.30 p.m. So the time will be 12.40 p.m 

Question 2.What is the longitude of a place where the local time 1:15 p.m. when it is 4 a.m. at

Chicago (88°W) ?

Answer:

The time difference between the two places is 9 hours and 15 minutes or 540 + 15 =

555 minutes So the longitudinal difference will be 555/4 = 138.75° degrees. So the

longitude of the required place will be 50° 45′ E i.e. it will cover 88° from west to 0° and

50° 45 east from 0° or Greenwich line.

Question 3.Calculate the time at Durban (longitude 30°E) when the time is 7.00 a.m. at New York (75°W).

Answer:

The longitudinal difference between Durban and New York is 30° + 75°= 105°, so the

time will be 105 x 4 = 420 minutes ahead from New York. There is the difference of 420

minutes or 7 hours, or 2 p.m.

Question 4.Calculate the longitude of a place where the local time is 6.00 a.m., when the time is 9.00 p.m. at New Delhi on longitude 77° E.

Answer:

The time difference between the required place and New Delhi is 6 + 9 = 15 hours, so

the time in minutes =15 × 60 = 900 minutes So the longitudinal difference = 900/4 =

225°. So the place will be in the west 225° – 77° = 148° W.

Question 5.Calculate the local time at Singapore (104°E) when it is 6.00 p.m. at Greenwich.

Answer:

The longitudinal difference at Singapore and Greenwich is 104°, so the time difference

is 104 × 4 = 416 minutes i.e. 6 hours 56 minutes. So the time at Singapore will be 12.56

a.m.

Question 6.Calculate the location of a place where the local time is noon when it is 7.30 p.m. at Greenwich.

Answer:

Time difference is 12 – 7.30 = 4.30 or 4 hours 30 minutes = 240 + 30 = 270 minutes So

the longitudinal difference is 270/4 = 67.5°. So the longitude is 67.5°W or 67 1/2° W. 

Question 7.What is the time and day at Mumbai (73°E) when it is Sunday 10.30 p.m. at Shillong (92°E) ?

Answer:

The longitudinal difference is 92° – 73° = 19°. So the time difference is 19 x 4 = 76

minutes or 1 hours 16 minutes or the time at Mumbai is 9.14 p.m