Fill in the following blanks with suitable words :
When a disc painted with the seven colours of rainbow is rotated rapidly, it appears to be _____________.

Answer

To fill in the blank in the statement, we can follow these steps:

1. **Understand the Concept of White Light**: Recognize that white light is made up of seven colors, which are red, orange, yellow, green, blue, indigo, and violet. These colors are the constituents of white light.

2. **Identify the Effect of Rotation**: When a disc painted with these seven colors is rotated rapidly, the colors do not remain distinct. Instead, they blend together due to the speed of rotation.

3. **Determine the Resulting Color**: As the colors mix together, they create a perception of a single color. When all the colors of the rainbow are mixed, they appear to form white light.

4. **Complete the Sentence**: Based on the understanding that mixing the seven colors results in the appearance of white light, we can fill in the blank.

The completed statement is: "When a disc painted with the seven colors of rainbow is rotated rapidly, it appears to be **white**."