Q3 of 10 Page 232

Fill in the blanks:

The special methods adopted to determine very large distances are _________and (Laser pulse method, Light year method, Radio echo method, Astronomical method)


Radio echo method, Laser pulse method.

Explanation: Radio echo method using three receivers spaced on the ground by 4 km has been used to determine the orbits of individual meteors.


In laser pulse method, a laser pulse is reflected from the object frim which distance is to be measured. The time taken is measured and using the speed of light, the distance is calculated.


More from this chapter

All 10 →
1

Correct the mistakes if any, in the following statements:

i) Astronomical unit is the mean distance of the surface of the sun from the surface of the earth.


ii) Light year is the distance travelled by light in one year in vacuum at a speed of 3x108m per minute.


 2

Match the items in group A with the items in group B:

































Sl.No.



Group – A



Group – B



1.



Small dimensions



Kilometre



2.



Large dimensions



Screw gauge



3.



Long distance



Scale



4.



Small distance



Light year



Altimeter



 4

Least count of a screw gauge is an important concept related to screw gauge. What do you mean by the term least count of a screw gauge?

 5

Label the following parts in the given screw gauge diagram.


i) Head scale ii) Pitch scale


iii) Index line iv) Ratchet