1. An object 20 cm away from a lens produces a focused image on a film 15 cm away, what is the focal length
of the converging lens? (8.5 cm)

8.6 cm

Explanation:

Step 1:

In this we have to find the focal length of converging lens.

To find focal length we have,

where u = Object distance

           v= Image distance

           f = Focal length

Step 2:

(1/f) =  0.116

f = 1/0.116

f = 8.6 cm

the word that best describes martin luther king jr.'s tone in the video is dignified

martin luther king, jr. was a social activist and baptist minister who played a key role in the american civil rights movement from the mid-1950s until his assassination in 1968. the video shows his manner and attitude having or showing a composed or serious manner that is worthy of respect so dignified is the correct answer