Physics
What is refractive index ?

It is defined as the product of speed of light in medium and in vacuum.
It is defined as the ratio of speed of light in vacuum to the speed of light in the medium.
It is defined as the ratio of speed of light in the medium to the speed of light in vacuum.
None of above

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Physics
Should cars have bumpers that collapse under impact?

No, since it would be very expensive to get the car repaired
No, since the colliding car would then ram into the occupants and kill them
Yes, since they help to absorb the impact of a collision and keep the occupants safe
Yes, since the offending car should get damaged and pay for the mistake

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