اختبار الكتروني درس Lenses

1
Lenses used in the .........
2
Concave lens is called .......lens
3
The convex lens...
4
The straight line that joins between the two centres of curvature of the lens and passes through its optical centre is called......
5
To determine the focal length of a lens,the mathematical relationship .....can be used
6
From the opposite figure,the radius of curvature is .....
7
If the focal length of a concave lens is 6 cm ,the radius of curvature is....
8
A convex lens , the distane between its focus and its optical centre is 10cm ,so the double of the focal length is.........
9
If the radius of curvature of a lens is 40cm its focal length equals.......
10
If the distance between the two centres of curvature of the lens is 20 cm ,this means that the focal length is.......

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