Question

 Fig. 12.1 shows a ray of light refracted as it enters a glass block.

(a) Use Fig. 12.1 to calculate the refractive index of the glass block.
Give your answer to 3 significant figures.

refractive index = ………………………………………………… 
(b) Fig. 12.2 shows how the refractive index of glass varies with the wavelength of light used.

(i) Use Fig. 12.2 to determine the wavelength of light used in Fig. 12.1.

                                wavelength = …………………………………………….. m 

(ii) Violet light has a wavelength of 4.0 × 10$^{-7}$m.
Red light has a wavelength of 7.0 × 10$^{-7}$m.
Describe how Fig. 12.2 shows that red light travels faster through glass than violet light.
………………………………………………………………………………………………………………………….
………………………………………………………………………………………………………………………….
(c) Fig. 12.3 shows the dimensions of the glass block.

The density of glass is 2.80g/cm$^{3}$.
Use Fig. 12.3 to calculate the mass of the glass block.

                                       mass = ……………………………………………… g 

▶️Answer/Explanation

Ans:  12(a) (n =) sin i / sin r or sin 53°/sin 31° ;
(n =) 1.55 ;

12(b)(i) (wavelength =) 4.8×10$^{-7}$(m) ; 
12(b)(ii) refractive index is inversely proportional to speed ; 
12(c) (volume =) 144 (cm$^{3}$ ) ;
(mass =) 2.8(0) × 144 ;
(mass = ) 403 (g) ;