# data[].attributes.body
positive- virtual image
negative- real image

# data[].attributes.headline
Focal length of concave lenses are NEGATIVE

# data[].attributes.subject
Focal length of concave lenses are NEGATIVE

# data[].attributes.headline
Focal length of convex lenses are POSITIVE

# data[].attributes.subject
Focal length of convex lenses are POSITIVE

# data[].attributes.body
Optical center: The center of the lens

Centre of Curvature: The center of the two spheres of which the lens is a part of

# data[].attributes.body
Convex Lens: Thicker at the center, thinner at the ends
Concave Lens: Thinner at the center, thicker at the ends