What causes light rays to bend in a new medium?

Here's what I think:

The phenomenon is rather complex and not real intuitively clear. I do believe however that your best answer is A.) CHANGE IN VELOCITY. Here's why: light is both a wave and a particle (photon) in the form of an electromagnetic wave with a magnetic wave component perpendicular to it. The 'wave' and 'particle' do not exist at the same time. Light is a wave when it is traveling through a vacuum and a particle (photon) when it strikes something (matter), and is absorbed or emitted by a different medium other than a vacuum.

We know that a light wave moving in a vacuum travels at the one constant speed of 3.0 x 10^8 m / sec., and when it enters a second medium of different refraction index than that of a vacuum, it seems to instantly slow down while passing through this new medium. When the light beam reaches the end of this new medium, it is emitted at the speed of light in a vacuum, instantly. I believe the reason for that instantaneous velocity at light speed in a vacuum is because: the electromagnetic component of the wave enters the second medium in the form of photon particles. These photons get absorbed, bounced around, and re-emitted by atoms in the second medium, a lot. Thus the photons of light are delayed by this subatomic behavior, until the photons reach the end of the second medium and are instantly emitted as 'waves' of light. In addition, I believe that it is only the electromagnetic component of the light wave that enters the second medium, not the magnetic component. The magnetic component continues on its way at the normal speed of light in a vacuum. That's why the electromagnetic component can instantly exit the second medium 'at' the speed of light. Here's the reason I think my hypothesis is correct: The electromagnetic component of light is in the form of a vector (possessing both magnitude and direction; the magnetic component of light however is in the form of a scalar and possesses only magnitude at every point in space-time. A scalar field cannot be block or shielded against, not so for a vector field.

That's what I think.

See: 2 Waves. the Wave Equation and Phase Velocity

http://www.geo.mtu.edu/~scarn/teaching/GE4250/Comp...

See: Propagation Fundementals-Plane wave & Poynting vector ...

http://www.mike-willis.com/Tutorial/PF3.htm

See: The Speed of Light and the Index of Refraction

http://www.rpi.edu/dept/phys/Dept2/APPhys1/optics/...

Best regards

A . Change in velocity

Refractive index(RI) decides it

R I = C/V

where C = velocity of light in vaccume (or approximately in air)

V = velocity of light in new medium

also

R I = sin i/ sin r (i = angle of incidene and r = angle of refraction) = C/V

if R I is more, bending of light is larger.

A. change in velocity