Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : The diameter of colloidal particles in solution should not be much smaller than wavelength of light to show Tyndall effect.
Reason R : The light scatters in all directions when the size of particles is large enough.
In the light of the above statements, choose the correct answer from the options given below:
Assertion A : The diameter of colloidal particles in solution should not be much smaller than wavelength of light to show Tyndall effect.
Reason R : The light scatters in all directions when the size of particles is large enough.
In the light of the above statements, choose the correct answer from the options given below:
- (A)A is true but R is false
- (B)A is false but R is true
- (C)Both A and R are correct and R is the correct explanation of A✓ Correct
- (D)Both A and R are correct but R is NOT the correct explanation of A
Answer: (C)
Solution
The Tyndall effect is the scattering of a light beam by dispersed particles, and it appears only when the particle diameter is of the same order as, and not much smaller than, the wavelength of the light used; this is exactly what Assertion A states, so A is correct. When the particles are this large they offer enough of a surface to deflect the incident light, scattering it in all directions and making the beam visible, whereas particles far smaller than the wavelength scatter negligibly. Reason R states this very scattering condition, which is the physical cause of the size requirement in A, so R is correct and is the correct explanation of A.
JEE Main · 2023 · 13 Apr 2023 · Shift 2 · Single correct option