23. NCERT Exemplar X

1. How are we able to see nearby and also the distant objects clearly?

 

Our eyes can change the angle of incidencefocal lengthangle of refraction of the lens and hence it can focus on the images from same distancevaried distance. PupilRetinaCorneaCiliary muscles help in changing the focal length of the lens.

 

2. Is the position of a star as seen by us its true position? Justify your answer.

 

YesNo.

 

The light form the star undergoes continuous dispersioncontinuous refractioncontinuous reflection on entering the earth’s atmosphere. It occurs in a medium of gradually changing refractive indexsame refractive index. The apparent position of the star is slightly different from its actual positionsame as its actual position because the light form the star is straightbend towards the normal as it travels through the atmosphere. The star appears same asslightly lower thanslightly higher than its actual position.