a beam of light is traveling through a medium at 200,000 km/s. it enters a different medium and speeds up to…

a beam of light is traveling through a medium at 200,000 km/s. it enters a different medium and speeds up to almost 250,000 km/s. finally, it enters a third medium and halts.\nwhat were the media the light traveled through, in order?\n○ liquid, opaque solid, gas\n○ opaque solid, gas, liquid\n○ gas, liquid, opaque solid\n○ liquid, gas, opaque solid
Answer
Brief Explanations:
To solve this, we recall the speed of light in different media: light travels slowest in solids, faster in liquids, and fastest in gases (in a vacuum it's fastest, but among these media, gas is faster than liquid, liquid faster than solid). Also, an opaque solid would stop light (halt it).
- First medium: speed 200,000 km/s – this is slower than gas (where light is faster) but faster than solid. So likely liquid (since liquid is slower than gas, faster than solid).
- Second medium: speeds up to ~250,000 km/s – gas is faster than liquid, so this should be gas.
- Third medium: light halts – opaque solid (since opaque solids don't transmit light, they stop it).
So the order is liquid (first), gas (second), opaque solid (third), which matches the option "liquid, gas, opaque solid".