Geography
Assertion (A): There is a time difference of a full day on crossing the IDL.
Reason (R): It is diametrically opposite the Greenwich Meridian.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R does not explain A.
- A is true but R is false.
- A is false but R is true.
Answer
Both A and R are true and R is the correct explanation of A.
Explanation — The line of longitude 180° or IDL is one and the same for East or West of the Prime Meridian. Since it is diametrically opposite to the Greenwich Meridian it causes a time difference of a full day on crossing the line. The time difference works out to 12 hours (180° x 4 min) from either side. Thus, on crossing the line, a day is gained or lost.
Related Questions
A great circle is a circle drawn on the surface of a sphere with radius :
- equal to the radius of the sphere.
- equal to half the radius of the sphere.
- larger than the radius of the sphere.
- less than the radius of the sphere.
Which of the following are great circles?
- Lines of Longitudes
- Lines of Latitudes
- Equator
- Both (1) and (3)
Assertion (A): Great circles are used to find the shortest distance between any two points on the earth's surface.
Reason (R): Great circle routes take into account weather or political restrictions.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R does not explain A.
- A is true but R is false.
- A is false but R is true.
What is a geographic grid? How does the geographic grid serve the same purpose as co-ordinates on a graph?