TJC H1 PHY P2

TEMASEK JUNIOR COLLEGE 2016 Preliminary Examination Higher 1 CANDIDATE NAME CIVICS GROUP INDEX NUMBER PHYSICS Paper 2 Structured Questions Candidates answer on the Question Paper. No Additional Materials are required. 8866/02 31 August 2016 2 hours READ THESE INSTRUCTION FIRST Write your Civics group, index number and name on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. Section A Answer all questions. Section B Answer any two questions. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Section A 1 2 3 4 5 Section B 6 7 8 Total This document consists of 24 printed pages.

2 Data speed of light in free space, c = 3.00 × 108 m s1 elementary charge, e = 1.60 × 1019 C the Planck constant, h = 6.63 × 1034 J s unified atomic mass constant, u = 1.66 × 1027 kg rest mass of electron, me = 9.11 × 1031 kg rest mass of proton, mp = 1.67 × 1027 kg acceleration of free fall, g = 9.81 m s2 Formulae uniformly accelerated motion, s = 21 2ut at 2v = 2 2ua s work done on/by a gas, W = p V hydrostatic pressure, p = ρgh resistors in series, R = 12RR   resistors in parallel, 1 R = 1211 RR  

3 Section A Answer all the questions in this section. 1 A bomber, shown in Fig. 1.1, is flying horizontally at a speed of 72 m s -1 and at a height of 100 m above the ground. When directly flying over the origin O, bomb B is released and it strikes a truck T, which is moving along a level road with a constant speed v. At the instant the bomb is released, the truck T is at a distance x o = 125 m from origin O. Fig. 1.1 (a) Define acceleration. [1] (b) Write an expression, in terms of the quantities given, (i) the horizontal displacement x of bomb B at time t after it is dropped, [1] (ii) the vertical displacement y of bomb B at time t after it is dropped. [1] (c) Calculate the time of flight of bomb B upon striking the truck T. time of flight = s [2]

4 (d) Determine the speed v of truck T. v = m s -1 [2] 2 (a) State Newton’s first law of motion. [1] (b) A uniform ladder of length 12.0 m and mass 40 kg rest on a wall. The lower end of the ladder is at 6.0 m from the wall as shown in Fig. 2.1. The wall is smooth while the ground is rough. 6.0 m Fig. 2.1 12.0 m

5 A man of mass 72 kg starts to climb up the ladder. When the man is ¾ way up the ladder, he feels that the ladder is beginning to slip. (i) On Fig 2.1, sketch the free-body diagram of the ladder, indicating all forces clearly. [2] (ii) Calculate the normal contact force by the ground on the ladder. normal contact force = N [2] (iii) Calculate the normal contact force by the wall on the ladder. normal contact force = N [2]

6 3 (a) Define electrical resistance of a conductor. [1] (b) Fig. 3.1 shows a circuit containing five identical lamps A, B, C, D and E. The circuit also contains three switches S1, S2 and S3. Fig. 3.1 One of the lamps is faulty. In order to detect the fault, an ohm-meter (a meter that measures resistance) is connected between terminals X and Y. When measuring resistance, the ohm-meter causes negligible current in the circuit. Fig. 3.2 shows the readings of the ohm-me ter for different switch positions. The resistance of the non-faulty lamps can be assumed to be constant. switch metre reading S1 S 2 S 3 / Ω open open open  closed open open 30.0 closed closed open 22.5 closed closed closed 15.0 Fig. 3.2 A X B CD E S1 S2 S3 Y

7 (i) Explain how it can be deduced from the results in the table that the resistance of each lamp is 15 Ω. [1] (ii) Identify the faulty lamp and the nature of the fault. faulty lamp: nature of fault: [2] (iii) Suggest why it is advisable to test the circuit using an ohm-meter that causes negligible current rather than with a power supply across terminals X and Y. [1] (iv) Each lamp is marked 12.0 V, 0.50 A. Calculate the resistance for one of the lamps operating at normal brightness. resistance = Ω [1] (v) Explain why the resistance calculated in (iv) is different from the value obtained in (i). [1]

8 4 (a) Define magnetic flux density. [1] (b) (i) Fig. 4.1 shows the cross-section of a conductor which carries a constant current flowing out of the plane of the paper. Sketch the magnetic field pattern due to the current. Fig. 4.1 [2] (ii) The current-carrying conductor is placed in the region between the poles of a strong magnet as shown in Fig. 4.2. Sketch on Fig. 4.2 the resultant magnetic field pattern in the region between the poles of a magnet. Fig. 4.2 [2] (iii) State the direction of the magnetic force acting on the current-carrying conductor. [1]

9 (iv) The magnetic flux density of the uniform field between the poles of the strong magnet is 0.50 T. The current in the conductor is 1.5 A and the length of the conductor that lies within the magnetic field is 0.10 m. Calculate the magnetic force acting on the current-carrying conductor. magnetic force = N [1] 5 A photoresistor or light dependent resistor (LDR) is a resistor whose resistance decreases with increasing incident light intensity; in other words, it exhibits photoconductivity. An LDR is made of a high resistance semiconduct or. If light falling on the device is of sufficiently high frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electron (and its hole partner) conduct electricity, thereby lowering resistance. The electrons released from bonds in the material of the LDR by absorbing incident photons remain free to conduct for about 50 ms before returning to be localised in bonds again. Fig. 5.1 shows a plot of the resistance R of the LDR against the intensity I of incident light on a logarithmic scale. Fig. 5.1 

10 (a) (i) Use Fig. 5.1 to find the resistance of the LDR at a light intensity of 50.0 W m–2. resistance of LDR =  [1] (ii) Explain the advantage of plotting the resistance-intensity graph on the logarithmic scale. [1] (iii) It is thought that the resistance R of the LDR is related to the intensity I of incident light by a relation of the form 110000  IR . Explain how the relation may be verified using Fig. 5.1. [2]