Sometimes a person cannot clearly see objects close up or far away. to correct this type of vision, bifocals are often used. the top half of the lens is used to view distant objects and the bottom half of the lens is used to view objects close to the eye. a person can clearly see objects only if they are located between 34 cm and 171 cm away from her eyes. bifocal lenses are used to correct her vision. what power lens (in diopters) should be used in the bottom half of the lens to allow her to clearly see objects 25 cm away?

Top Half power is

Bottom half power

Explanation:

For the top part of the lens we need a focal length of the lens in which person can see upto a large distance

so here we have

now by lens formula

now we have

now power of top part of the lens is given as

Now for the bottom half we can say

now by lens formula

what type of charge does it have? negative

the simple machine has three main features. they are:

fulcrum is the center point or pivot point of the machine. effort is input force/ applied force. load is external force/ output.

the keisha 's machine labels are

x : load

y: fulcrum

z: lever