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In the 17th century, Isaac Newton proposed a theory to explain some of the properties of light - AQA - A-Level Physics - Question 1 - 2022 - Paper 7
Question 1
In the 17th century, Isaac Newton proposed a theory to explain some of the properties of light. An alternative theory of light was proposed by Christiaan Huygens at ... show full transcript
Worked Solution & Example Answer:In the 17th century, Isaac Newton proposed a theory to explain some of the properties of light - AQA - A-Level Physics - Question 1 - 2022 - Paper 7
Step 1
Explain how this observation supports Newton’s theory of light.
Answer
Newton's theory suggests that light consists of particles (corpuscles) that travel in straight lines. The observation of two bright white lines on the screen indicates that light behaves predictably, creating shadows with well-defined edges. This aligns with Newton's notion of particle behavior, as it supports the idea of light traveling in straight lines and forming distinct shadows.
Step 2
Identify the alterations made by the student and explain how the observations in Figure 2 support Huygens’ theory of light.
Answer
The student likely altered the apparatus by using a monochromatic light source or by placing a filter to create a coherent light wave. The observations in Figure 2 show red and dark fringes, which demonstrate the wave nature of light. According to Huygens' theory, every point on a wavefront acts as a source of secondary wavelets. The resulting interference pattern confirms Huygens' model, where light waves overlap and create regions of constructive and destructive interference.
Step 3
Discuss these differences in appearance.
Answer
Newton's theory predicts that light should appear as well-defined bright spots due to the particle nature, leading to distinct shadow patterns. In contrast, Huygens' theory suggests that light will create fringes or bands due to wave interference. Grimaldi’s setup demonstrates that the combination of apertures results in a more complex pattern, supporting the idea of light behaving as a wave, thereby resulting in differing appearances on the screen.