iGCSE Physics (0625) 3.2.4 Dispersion of light -Exam Style Questions paper 1 - New Syllabus
▶️ Answer/Explanation
Detailed solution:
When white light undergoes dispersion through a glass prism, violet light is refracted the most and red light the least.
Therefore, the spectrum on the wall will have red at the top (Y) and violet at the bottom (X), with green in the middle (Z).
Option C correctly assigns red to Y, green to Z, and violet to X.
This aligns with the known order of increasing frequency and decreasing wavelength from red to violet.
▶️ Answer/Explanation
Detailed solution:
When white light enters a glass prism, it undergoes refraction at the boundaries. Because different colors of light have different frequencies, they travel at different speeds within the glass. This causes each color to refract by a slightly different angle, a phenomenon known as dispersion. Consequently, the white light splits into its constituent seven colors of the visible spectrum. Diffraction involves the spreading of waves through gaps, while reflection involves light bouncing off surfaces. Thus, the correct term for the splitting of light into a spectrum is dispersion.
▶️ Answer/Explanation
Detailed solution:
The visible spectrum consists of seven main colours, often remembered by the acronym $ROYGBIV$.
In order of increasing wavelength (from shortest to longest), the sequence is: Violet, Indigo, Blue, Green, Yellow, Orange, and Red.
Conversely, this means Red has the longest wavelength and Violet has the shortest wavelength in the visible range.
Option A follows this sequence correctly: Green is followed by Yellow, then Orange, and finally Red.
Options B, C, and D are incorrect as they do not follow the $V \rightarrow I \rightarrow B \rightarrow G \rightarrow Y \rightarrow O \rightarrow R$ progression for increasing wavelength.