CIE iGCSE Co-Ordinated Science C9.1 Properties of metals Exam Style Questions Paper 4
Question
Fig. 9.1 shows two identical infrared heating lamps that are heating two metal cubes. The lamps
are at the same distance from the cubes. The lamps are heating each cube for the same time.
One lamp is heating the dull white metal cube and the other the dull black metal cube.
(a) (i) Explain why the temperature of the dull black cube rises more than the temperature of
the dull white cube.
(ii) The dull black metal cube is replaced by a shiny black metal cube.
Explain why the temperature of the shiny black cube rises less than the temperature of
the dull black cube.
(iii) Infrared radiation emitted by the lamps includes radiation with a wavelength of 0.75mm.
Calculate the frequency of this infrared radiation.
frequency = ……………………………………………. Hz
(iv) Thermal energy is conducted through the metal cubes.
Describe the process of conduction in a metal.
(b) One of the cubes is now filled with hot water. A student uses a digital thermometer containing
a thermocouple to measure the temperature of the water inside the cube.
(i) Describe the structure of a thermocouple used to measure temperature.
(ii) The thermocouple produces an electromotive force (e.m.f.).
Place ticks (✓) in Table 9.1 to compare e.m.f. to potential difference.
▶️Answer/Explanation
Ans : 9(a)(i) dull black (cube) absorbs (thermal / infrared) radiation better than dull white (cube) ; 9(a)(ii) shiny black (cube) reflects radiation (rather than absorbs as the dull surface of black cube does) ;
9(a)(iii) use of 3.0 × 108
(m / s) ;
(f =) v / λ / 3.0 × 108
/ 0.75 × 10–3
;
(f =) 4.0 × 1011 (Hz) ;
9(a)(iv) vibrations (of ions / atoms) ;
passes from one ion / atom to the next ;
also by electrons moving through metal ;
9(b)(i) two different metal wires joined at two junctions at different temperatures ;
9(b)(ii) electromotive force and potential difference ticked ;
electromotive force and potential difference ticked ;
electromotive force only ticked ;