A light which has vibrations in all directions in a plane perpendicular to the direction of propagation is said to be unpolarised light. The light from the sun, an incandescent bulb or a candle is unpolarised.
If the electric field vector of a light wave vibrates just in one direction perpendicular to the direction of wave propagation, then it is said to be polarised or linearly polarised light.
Yes, the intensity of polarised light emitted by a Polaroid depends on orientation of Polaroid. When polarised light is incident on a Polaroid, the resultant intensity of transmitted light varies directly as the square of the cosine of the angle between polarisation direction of light and the axis of the Polaroid.
I∝ cos2θ or I=I0 cos2θ
Where I0 = maximum intensity of transmitted light;
θ = angle between vibrations in light and axis of Polaroid sheet.
or, I=I0 cos2 600=I04
Percentage of light transmitted = II0×100=14×100=25%