Expert Answers

1) It takes a laser light 25 sec to go to moon & reflect back to earth. Knowing the speed of light can we determine the distance between the earth and the moon? a) yes it's possible to determine or b) no it is not possible. If possible, what'll be the distance between the moon & earth? ____________________     

2) There are three lenses, two convex and one concave. Lens A, f1=9cm, Lens B, f2=18cm and Lens C, f2=-9cm
Which of the three lenses will focus the light from relatively far distance?
a) Lens A, b) Lens B, or c) lens C (there could be more than one answer)

3) For the far light, what will be the distance the light will focus for the 3 lenses?
a) Lens A:____________
b) Lens B:____________ and
c) Lens C:_____________

               
4) If Lenses A and B are stacked together, what will be the effective focus distance for the light? ( f-combined = (f1 xf2)/(f1+f2) )
a) Larger or equal to 18cm b) less than or equal to 9cm c) between 9cm and 18cm. Actual focal distance: __________________

5) If lenses B & C combined, what will be the effective focus point for the two lenses? ( f-combined = (f2 x f3)/(f2-f3) )
a) Larger or equal to 18cm b) less than or equal to 9cm c) between 9cm and 18cm. Actual focal distance: __________________