Two thin lenses of power and are placed in contact. Find the power of the lens combination. Also, calculate the focal length of the combination.
Step 1: Given data,
Power of lens 1 is
Power of lens 2 is
Step 2: Finding the power of the lens combination,
According to power of lens combination formula,
Substituting the know values,
Thus, the power of the lens combination is .
Step 3: Finding the focal length of lens 1,
According to the power of lens formula,
where is the focal length of the lens 1
Substituting the known values,
Thus, the focal length of lens 1 is .
Step 4: Finding the focal length of lens 2,
According to the power of lens formula,
where is the focal length of the lens 1
Substituting the known values,
Thus, the focal length of the lens 2 is .
Step 5: Finding the focal length of the lens combination,
According to the focal length of the lens combination formula,
where, is the focal length of lens combination.
Substituting the known values,
Thus, the focal length of the lens combination is .