How much light is refracted through glass?

Correct answer: c 96%

Ordinary glass sends back only about 4% of the light, so the other 96% is refracted and passes in.

Why the other options are wrong

• a 4%: 4% is the part that comes back (is reflected) from glass, not the refracted part. The remaining 96% or so goes into the glass.
• b 5%: 5% is the upper end of the reflected share (4% to 5% in glass), not the refracted share. Most of the light goes in, about 96%.
• d 100%: Some light is always reflected as well, so not all of it goes in. About 4% comes back from glass and 96% enters.