RI 2021 Y6 H2 Phy T3 CT QP B

© Raffles Institution [Turn over Name: ( ) CT Group: 21S0 RAFFLES INSTITUTION 2021 YEAR 6 JULY COMMON TEST H2 PHYSICS RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFL ES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFL ES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFL ES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFL ES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFLES INSTITUTION RAFFL ES INSTITUTION I Section B INSTRUCTIONS TO CANDIDATES Write your name, index number and CT Group. Write your answers to Section B in the spaces provided in this booklet. For Examiner’s Use Section A MCQ / 20 Section B 21 / 9 22 / 9 23 / 9 24 / 9 25 / 9 26 / 10 27 / 20 Deductions Total / 95 There are 21 printed pages, inclusive of the cover page, in this booklet.

2 © Raffles Institution Section B 21 (a) Hot air balloons used to be a means of transportation through the air. They are now commonly used for altitude sightseeing. The hot air balloon illustrated in Fig. 21.1 contains 800 m 3 of air at a constant temperature of 400 K. The density of the air at this temperature is 0.905 kg m−3. The air in the balloon was heated up from its initial temperature of 273 K at constant pressure and the specific heat capacity of the air under the conditions in which it wa s heated is 1050 J kg−1 K−1. (i) Calculate the mass m of air in the balloon at 400 K. m = kg [1] (ii) Determine the heat Q required to raise the temperature of the mass m of air from 273 K to 400 K. Q = J [1] (iii) The density of air is inversely proportional to its thermodynamic temperature at a constant pressure. Show that the density of air at 273 K is 1.33 kg m−3. [1] Fig. 21.1

3 © Raffles Institution [Turn over (iv) Hence, determine the volume which mass m of air occupies at 273 K. volume = m3 [1] (b) Fig. 21.2 shows that, during the heating process, air which was originally within the balloon spills out from the balloon. Calculate the work done on the atmosphere during this process. Atmospheric pressure is 1.03 × 105 Pa. work done = J [1] (c) Calculate the change in the internal energy of the mass m of air when heated from its initial temperature of 273 K to its final temperature of 400 K. change in the internal energy = J [2] (d) State two reasons why in reality, your answer in part (a)(ii) is an underestimate of the amount of heat required to raise the temperature of the mass m of air from 273 K to 400 K. 1. 2. [2] air which expands to fill balloon at 400 K air which spills out of balloon as temperature inside rises from 273 K to 400 K Fig. 21.2

4 © Raffles Institution 22 A piece of bare resistance wire XY of uniform diameter of 0.052 mm is mounted on a metre rule such that X and Y are at the 0 cm and 100 cm markings respectively. XY is then connected in series to a cell of electromotive force (e.m.f.) 12.0 V with negligible internal resistance and a 2.0 Ω fixed resistor. (a) A voltmeter is connected across points A and B on the wire as shown in Fig. 22.1 where A and B are at 25 cm and 75 cm markings respectively. The reading on the voltmeter is 3.0 V. (i) Calculate the resistance of wire XY. resistance of wire XY = Ω [2] (ii) Determine the resistivity of wire XY. resistivity = Ω m [2] Fig. 22.1 X Y A B 12.0 V 2.0 Ω V

5 © Raffles Institution [Turn over (b) The voltmeter is replaced by another cell E and a sensitive ammeter as shown in Fig. 22.2. Cell E has negligible internal resistance. When the contact at B is moved such that length L is 30.0 cm, the ammeter reads zero. Determine the e.m.f. of cell E. e.m.f. = V [1] (c) State and explain how the balance length L will change if (i) a fixed resistor R is placed in series with E as shown in Fig. 22.3. [2] Fig. 22.3 X Y L E R 12.0 V 2.0 Ω sensitive ammeter Fig. 22.2 X Y L E A B 12.0 V 2.0 Ω sensitive ammeter

6 © Raffles Institution (ii) the 12.0 V battery has internal resistance r as shown in Fig. 22.4. [2] Fig. 22.4 X Y L E r 12.0 V 2.0 Ω sensitive ammeter

7 © Raffles Institution [Turn over 23 (a) Define magnetic flux density. [1] (b) A long wire P is at right angles to the plane of the paper and carries a current out of the plane of the paper as shown in Fig. 23.1. On Fig. 23.1, sketch the pattern of the magnetic field around wire P in the plane of the paper. [2] (c) A long wire Q, at right angles to the plane of the paper is placed at a distance of 0.25 m from wire P as shown in Fig. 23.2. Wire P carries a current of 2.0 A out of the plane of the paper and wire Q carries a current of 3.0 A into the plane of the paper. (i) Calculate the magnetic flux density BP due to the current in wire P at wire Q. BP = T [2] x P Q Fig. 23.2 0.25 m 3.0 A 2.0 A P Fig. 23.1

8 © Raffles Institution (ii) Determine the force per unit length of wire experienced by wire Q. force per unit length of wire = N m−1 [2] (d) A third long wire R is placed along the line joining wire P and wire Q, at a distance of 0.25 m away from wire Q as shown in Fig. 23.3. Wire R carries a current of 4.0 A out of the plane of the paper. State and explain the direction of the resultant force experienced by wire Q due to the currents in wire P and wire R. [2] x P Q Fig. 23.3 0.25 m R 0.25 m 4.0 A 3.0 A 2.0 A

9 © Raffles Institution [Turn over 24 In an experiment to study the phenomenon of electromagnetic induction, a small coil Q is placed along the axis of a large coil P that carries a steady direct current as shown in Fig. 24.1. The coil Q is moved along the axis of the coil P at a constant speed s uch that an e.m.f. is induced in coil Q. The magnetic field is always perpendicular to the plane of coil Q. Fig. 24.2 shows how the magnitude of the magnetic flux density, B , produced by the coil P varies with the distance x from its centre along the axis. B/10−3 T 2 4 6 8 10 0 0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 x/m Fig. 24.2 A axis of coils coil Q direction of motion of coil Q x Fig. 24.1 coil P

10 © Raffles Institution (a) State and explain the direction of the induced current in the coil Q compared with that in the coil P as it is moved along the axis. [3] (b) In the experiment , coil Q is moved along the axis from the centre of coil P to a position x = 0.100m in 0.25s.