what is 2F₁,F₁,F₂,2F₂ stands for???

then why it is called 2F1???? whats wrong wid C??

F1 = F2 focal length

2f1=2f2 radius of curvature.

shreyasi, there is nothing wrong with C. but 2F₁ and 2F₂ are standard terms.

F1 and F2 are the focal points or the focus..The distance between the focal points and the optical centre of the lens is called the focal length.

2F1 an 2F2 are the centre of curveture.

f is focus and 2f is centre of curvature in lens

left side of lens

F1=FOCAS

2F1=CENTRE OF CURVATURE

RIGHT SIDE OF LENS

F2=FOCUS

2F2=CENTRE OF CURVATURE