[theCoolScientist (OP)]

All the effects like polarisation etc occur due to change in the varying electric field of the light,do u think there could be affects by changing the magnetic field connected to light?

[JP]

The electric and magnetic fields are two parts of the same underlying electromagnetic field.  One depends on the other and changing one influences the other.  We could vary the electric field of light by controlling its magnetic field, but the problem is that for the most part magnetism in matter isn't a large effect in matter at the high frequencies involved with visible light. 

[Bored chemist]

The simple answer is yes.

http://en.wikipedia.org/wiki/Faraday_effect

[acsinuk]

Wikipedia states that in the final paragraph
"The composite magnetic/plasmonic nanostructure can be visualized to be a magnetic particle embedded in a resonant optical cavity. Because of the large density of photon states in the cavity, the interaction between the electromagnetic field of the light and the electronic transitions of the magnetic material is enhanced, resulting in a larger difference between the velocities of the right- and left-hand circularized polarization, therefore an enhanced Faraday rotation."
The power grid runs at only 50 hertz but still the current moves at nearly the speed of light.  AC electric theory is easier to study than light and engineers are well aware that grid power is comprised of an area of current being pulled forward by a voltage at right angles to the current.  If the phase angle is incorrect then the power is reduced by the cosine of the angle and reactive current [ either inductive or capacitive] produces VAR's which are imaginary power instead of Watts.
CliveS

[Ian Scott ZL4NJ]

As a suggestion, if we extend our interpretation of "light" to include all electromagnetic radiation then both magnetic and electric field modifications will produce measurable effects. To illustrate, Erbium doped fiber optic cables, "pumped" by a laser are often used to amplify light signals used to carry high speed digital data over long haul communication systems. This amplification (I recall values around 20 dB of gain!) can also be demonstrated at longer wavelengths usually associated with radio frequencies. Parametric amplifiers, once used by early NASA moon missions (e.g. Apollo), were apparently used to amplify signals received by terrestrial dish antennas. These would have used Variable Capacitance Diodes (Varicaps) but were not all that "low noise" by modern standards, despite cryogenic cooling! The same amplification should occur if magnetic materials are used. If pumped using a suitable Local Oscillator (LO) source, then magnetically based amplification should occur. Whether this represents any usable application, given simpler and more effective alternatives is another matter! 

[ScientificSorcerer]

If you change the frequency of light waves then you change the color of the light.

If you change the electric field of light then you change the magnetic aspect of light too, the result of changing one will change the other. and if you change ether then you merely change the brightness of the light.

[lightarrow]

and if you change ether then you merely change the brightness of the light.

Please?