CIE iGCSE Co-Ordinated Science P3.2.2 Refraction of light Exam Style Questions Paper 4
Question
Fig. 6.1 shows a mobile phone (cell phone) on a wireless charging pad.
(a) The screen of the mobile phone is made from glass.
When light travels from air into glass it is refracted and changes direction.
(i) Place one tick ( √) in each row of Table 6.1 to state the effect on the properties of
frequency, speed and wavelength for light as the light travels from air into glass.
(ii) A ray of light is incident on the screen of the mobile phone.
The angle of incidence is 53°.
The refractive index of glass is 1.5.
Calculate the angle of refraction r.
r = ………………………………………………. °
(b) The mobile phone battery holds a maximum charge of 3300C.
The current used to charge the battery is 0.60A.
Calculate the time taken to fully charge the mobile phone battery.
time taken = ……………………………………………… s
(c) The wireless charging pad in Fig. 6.1 contains a coil of wire. The mains cable provides an alternating current (a.c.) to the coil of wire.
The mobile phone contains a second coil of wire.
Describe how an electromotive force (e.m.f.) is induced in the second coil of wire when the mobile phone is placed on the charging pad.
…………………………………………………………………………………………………………………………………
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▶️Answer/Explanation
Ans : 6(a)(i) (frequency) stays the same ;
(speed) decreases ;
(wavelength) decreases ;
6(a)(ii) evidence of sin i n =$\frac{sini}{sin r} $ or 1.5=$\frac{sini}{sin r} $ or 1.5 $\frac{sin 53}{sin r}$
32(°) ;
6(b) evidence of Q = It or 3300 ÷ 0.60 ;
5500 (s) ;
6(c) (idea that) there is a (changing) magnetic field around the coil of wire (in the charging pad) ;
the second coil experiences a changing magnetic field (which induces the e.m.f.) ;