NCERT Solutions for Class 8 Science Chapter 16
Important NCERT Questions
8th Chapter 16 Light
NCERT Books for Session 2022-2023
CBSE Board and State Board
Questions No: 3
Mention against each of the following whether regular or diffused reflection will take place when a beam of light strikes. Justify your answer in each case. (a) Polished wooden table (b) Chalk powder (c) Cardboard surface (d) Marble floor with water spread over it (e) Mirror (f) Piece of paper
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(a) A polished wooden table is an example of smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.
(b) Chalk powder has irregular surface. So, when a beam of light reflects from it, a diffused reflection will take place.
(c) A cardboard has irregular surface. So, when a beam of light reflects from it, a diffused reflection will take place.
(d) A marble floor with water spread over it provides a smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.
(e) A mirror has a smooth surface. So, when a beam of light reflects from it, a regular reflection will take place.
(f) A piece of paper may appear smooth but it has many minor irregularities. So, when a beam of light reflects from it, a diffused reflection will take place.
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(a) Polished wooden table: Regular reflection occurs due to the table’s smooth surface, following the laws of reflection precisely.
(b) Chalk powder: Diffused reflection happens because the rough and irregular surface of chalk powder scatters light in multiple directions.
(c) Cardboard surface: Diffused reflection occurs owing to the surface’s roughness, causing light to scatter in various directions.
(d) Marble floor with water spread over it: Both regular and diffused reflection occur. Smooth marble areas reflect light regularly, while rough or wet parts cause light to scatter.
(e) Mirror: Regular reflection occurs impeccably due to the mirror’s highly polished, smooth surface.
(f) Piece of paper: Diffused reflection happens as the paper’s surface, although seemingly smooth, possesses microscopic irregularities causing light to scatter in multiple directions.
Regular reflection takes place on smooth, polished surfaces, precisely following the laws of reflection. Conversely, diffused reflection occurs on rough or irregular surfaces, causing light to scatter in multiple directions rather than forming a clear, well-defined reflection.