Introduction:
Newton's disc is a rotating disc with different colors arranged in a specific sequence. When the disc is rotated at a high speed, it appears white due to the phenomenon of color mixing. In this response, we will explore what happens when one color is removed from the disc and how it relates to the experiment to study light traveling along a straight line.

Newton's Disc:
When the Newton's disc is rotated, the colors on the disc blend together due to the persistence of vision. This phenomenon occurs because our eyes retain an image for a short period of time, creating an illusion of color mixing. The colors on the disc are arranged in a specific order, typically in the sequence of red, orange, yellow, green, blue, indigo, and violet. As the disc spins, the colors merge and appear white to our eyes.

Removing a Color:
If we remove one color from the Newton's disc, the color sequence will be disrupted. When the disc is rotated, the missing color will create a gap in the sequence, and the colors adjacent to it will no longer blend together perfectly. As a result, the disc will not appear white when rotated. Instead, the remaining colors will mix together, but the absence of the removed color will be noticeable.

Relation to Experiment: Light Travels along a Straight Line:
The experiment to study light traveling along a straight line involves the use of a straight line, a source of light, and an opaque object. When light travels through a straight line, it propagates in a straight path until it encounters an obstruction. This can be demonstrated by placing an opaque object in the path of the light. The object will cast a shadow, blocking the light from reaching the surface behind it.

In the context of Newton's disc, the colors on the disc represent different wavelengths of light. When the disc spins, the colors merge together because the light from each color reaches our eyes before it has a chance to disperse. This phenomenon is similar to light traveling along a straight line, as the colors on the disc follow a specific sequence and blend together to create the appearance of white light.

Conclusion:
In conclusion, if we remove one color from Newton's disc, it will no longer appear white when rotated. The removal of a color disrupts the sequence and blending of colors, causing the disc to display a noticeable gap and the remaining colors to mix imperfectly. This observation is related to the experiment to study light traveling along a straight line, where the colors on the disc represent different wavelengths of light that merge together to create the illusion of white light.