If a spherical lens has a power of, $-0.25 \mathrm{D}$, the focal length of this lens will be:

The optical prescription for a pair of spectacles is:

Right eye: $-3.50 \mathrm{D}$

Left eye: $-4.00 \mathrm{D}$

Are these lenses thinner at the middle or at the edges?

The optical prescription for a pair of spectacles is:

Right eye: $-3.50 \mathrm{D}$

Left eye: $-4.00 \mathrm{D}$

Which lens has a greater focal length?

The optical prescription for a pair of spectacles is:

Right eye: $-3.50 \mathrm{D}$

Left eye: $-4.00 \mathrm{D}$

Which is the weaker eye?

A person got his eyes tested by an optician. The prescription for the spectacles lenses to be made reads:

Left eye: $+2.50 \mathrm{D}$

Right eye: $+2.00 \mathrm{D}$

State whether these lenses are thicker in the middle or at the edges.

A person got his eyes tested by an optician. The prescription for the spectacles lenses to be made reads:

Left eye: $+2.50 \mathrm{D}$

Right eye: $+2.00 \mathrm{D}$

Which lens bends the light rays more strongly?