Question
(a) Remote controllers for television sets send a beam of electromagnetic radiation to the television.
Which region of the electromagnetic spectrum is used? Tick one box.
microwaves 
infra-red 
visible 
ultra-violet 
X-rays [1]
(b) Modern warfare often uses heat-seeking missiles.
Which region of the electromagnetic spectrum is used? Tick one box.
microwaves 
infra-red 
visible 
ultra-violet 
X-rays [1]
(c) Injured legs may be checked for possible fractures using electromagnetic radiation.
Which region of the electromagnetic spectrum is used? Tick one box.
microwaves 
infra-red 
visible 
ultra-violet 
X-rays [1]
(d) Mobile phones communicate using electromagnetic radiation.
Which region of the electromagnetic spectrum is used? Tick one box.
microwaves 
infra-red 
visible 
ultra-violet 
X-rays [1] [Total: 4]
Answer/Explanation
Ans: (a) infra-red
(b) infra-red
(c) X-rays
(d) microwaves
Question
(a) Fig. 6.1 represents the electromagnetic spectrum.
State the radiation in each of the regions represented by A, B, C and D in Fig. 6.1.
A ……………………………………………………….
B ………………………………………………………
C ………………………………………………………
D ………………………………………………………
(b) A source emits visible light.
Fig. 6.2 shows a ray of red light from the source incident on the face XY of a glass prism at point S.
The angle of incidence i of the ray is 35 °. The refractive index of the glass for red light is 1.5.
(i) Calculate the angle of refraction in the glass at S.
angle of refraction = ……………………………………………………………………………
(ii) On Fig. 6.2, draw the refracted ray at face XY and the ray emerging from face XZ of the prism. Label this ray R.
(iii) A ray of blue light follows the same path as the ray of red light incident on the face XY.On Fig. 6.2, draw the path of this ray in the prism and emerging from the prism.
Label this ray B.
Answer/Explanation
Answer:
(a) A: infra-red B: ultra-violet C: X-(rays) D:γ-(rays)
(b)
(i) n = sin i / sin r
OR sin r = sin i / n OR sin r = sin 35 / 1.50
r = 22°
(ii) Refraction at XY drawn with r < i Refraction at XZ drawn with r > i
(iii) Blue ray drawn below red ray in prism and drawn with r < i
Ray to right of prism diverging downwards from red ray