In 2Cr2O7 there’s 2 items; Cr and O
High frequency , it is because wavelength is inversely proportional to frequency
Answer:
f = 1 m
Explanation:
The magnification of the lens is given by the formula:

where,
M = Magnification = 4
q = image distance = 5 m
p = object distance = ?
Therefore,

Now using thin lens formula:

<u>f = 1 m</u>