The correct option is (a).
Explanation
A kaleidoscope is an optical instrument that operates on the principle of multiple reflections. It creates beautiful, symmetrical patterns through the repeated reflection of light by inclined mirrors.
Statement-wise Analysis:
- Statement 1 is Correct: A standard kaleidoscope consists of three rectangular mirror strips of the same size. These strips are joined together with their reflecting surfaces facing inward to form a triangular prism. This arrangement ensures that multiple reflections occur, creating symmetrical patterns.
- Statement 2 is Incorrect: For the patterns to be visible, light must enter the tube. Therefore, one end of the tube is closed with a ground glass plate (translucent) or a transparent glass disc to allow light to pass through and illuminate the colored objects inside. If it were closed by a completely opaque metal plate, no light would enter, and no patterns would be visible. The other end contains a cardboard disc with a small hole for viewing.
- Statement 3 is Incorrect: The tube contains loose colored glass pieces or beads in the space between the glass plates. When the tube is rotated or shaken, these pieces tumble and rearrange themselves randomly. Consequently, the patterns formed are dynamic and never repeat exactly in the same sequence, offering a unique view each time.
Key Takeaway:
A kaleidoscope uses three inclined mirrors (forming a prism) to produce symmetrical patterns via multiple reflections. The patterns are non-repeating due to the random movement of the objects inside.