Where does the refraction occur when the light enters a different medium?

Explanation:

The speed of light when it travels through glass, diamond, etc, the light travels at different speed from the speed of light. Speed of the light in material is related to the index of refraction.

Hence, light have different speeds in different medium and also, will have different wavelength in different mediums.

The change in speed which occurs when the light passes from one medium to the another is responsible for bending of the light which is called as refraction.

Further, if the light travels from a low denser medium to high denser medium, it refracts towards the normal and if the light travels from high denser medium to low denser medium, it refracts away from the normal. The refraction of light happens at the point of incidence.

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation:

i don't understand. explain it clearly