A diver takes a thin symmetric biconvex glass lens of index
PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Geometrical optics and imaging · Geometrical optics and imaging
Optics and Photonics, Ch Image formation by mirrors and lenses
Problem
A diver takes a thin symmetric biconvex glass lens of index nl=1.55, with R1=+10 cm and R2=−10 cm under convention CV1 (light left to right; R>0 when the centre of curvature lies to the right of the vertex; so>0 for a real object on the left, si>0 for a real image on the right). On deck, in air (nm=1.00), a small bright lamp 20 cm to the left of the lens is imaged sharply on a white card. The whole arrangement, lamp and lens 20 cm apart, is then taken underwater (nm=1.33). Assume a thin lens, paraxial rays and one wavelength; use 1/f=(nl/nm−1)(1/R1−1/R2).
((a)) Before calculating, predict whether the diver can still catch the image on the card underwater, and give the reason in one sentence.
((b)) Compute f and si in air.
((c)) Compute f and si in water, and classify the image.