Why does light have greater velocity in rarer medium?

answer:

when light travels through a medium that is not empty, the photons interact with the other particles in its way, slowing the photon down.

explanation:

c because the action was the roller coaster reaches bottom of hill (action) reaction would be blood tends to drain away from head

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when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27