Name:……………………………………………………
No. IC:…………………………….
PENGGAL 2 960/2
STPM 2015
JABATAN PENDIDIKAN NEGERI KELANTAN SIJIL TINGGI PERSEKOLAHAN MALAYSIA
PHYSICS 2 (FIZIK 2) MODUL 1 One and a half hours ( Satu jam setengah) Instructions to candidates: DO NOT OPEN THIS QUESTIONS PAPER UNTIL YOU ARE TOLD TO DO SO. There are fifteen questions in Section A. For each questions, four choices of answers are given. Choose one correct answer and indicate it on the Multiple-choice Answer Sheet provided. Read the instructions on the Multiple-choice Answer Sheet very carefully. Answer all questions. Marks will not be deducted for wrong answers. Answer all questions in Section B. Write your answers in the spaces provided. Answer any two questions in Section C. All essential working should be shown. For numerical answers, unit should be quoted wherever appropriate. Begin each answer on a fresh sheet of paper and arrange your answers in numerical order. Tear off the front page of this question paper in your answer sheets of Section B, and tie both of them together with your answer sheets in Section C. Values of constant are provided. Answers may be written in either English or Bahasa Malaysia
For examiner’s use (Untuk kegunaan pemeriksa) Section A (Bahagian A)
Section B (Bahagian B) 16 17 Section C (Bahagian C)
Total (Jumlah) This question paper consists of 12 printed pages and 0 blank pages. (Kertas soalan ini terdiri daripada 12 halaman bercetak dan 0 halaman kosong.) 1
Section A [15 marks] Answer all questions in this section
1.
Which of the following physical quantities does not have a value of zero on the surface of an isolated conductor? A Electric potential at the surface B Current flowing on the surface. C Magnetic field near the surface. D Electric field along the surface.
2 Three charges are located along the x axis as shown in the drawing. The mass of the –1.2 μC is 4.0 × 10–9 kg. Determine the magnitude and direction of the acceleration of the –1.2 μC charge when it is allowed to move if the other two charges remain fixed. A 2 × 105 ms-2, to the right B 1 × 105 ms-2, to the left C 7 × 104 ms-2, to the right D 3 × 105 ms-2, to the left
3 A capacitor of capacitance 15µF is fully charged and the potential difference across its plate is 8.0V. It is then connected into the circuit as shown
The switch S is closed at time t = 0. Which one of the following statements is correct?
2
A the time constant of the circuit is 6.0ms. B The initial charge on the capacitor is 12µC. C After a time equal to twice the time constant, the charge remaining on the capacitor is Qoe2, where Qo ts the charge at timen t=0. D After a time equal to the time constant, the potential difference across the capacitor is 2.9V. 4. The circuit diagram shows two capacitors of capacitances 300 F and 500 F connected in series with a 6.0 V battery.
The charge in the 300 F capacitor is A 0.68 mC
C 1.8 mC
B 1.1 mC
D 4.8 mC
5 Which of the following circuits show a bridge circuit which is not in equilibrium?
3
6 In the circuit below, the ammeter reading is I and the voltmeter reading is V.
When of the switch is closed, which row describes what happens to I and V ?
I
V
A
decreases
decreases to zero
B
increases
decreases to zero
C
increases
stays the same
D
stays the same
increases
7 The principles of conservation of which two quantities are associated with Kirchhoff’s first and second laws? First Law Second Law A
charge
B
charge
C
energy
charge
D
voltage
charge
8
energy voltage
A conducting loop of wire is placed in a magnetic field that is normal to the plane of the loop. Which one of the following actions will not result in an induced current in the loop?
A Rotate the loop about an axis that is parallel to the field and passes through the center of the loop. B Increase the strength of the magnetic field. C Decrease the area of the loop. D Decrease the strength of the magnetic field.
4
9 The current in a solenoid is decreased to one-half of its original value. Which one of the following statements is true concerning the self-inductance of the solenoid? A The self-inductance does not change. B The self-inductance increases by a factor of two. C The self-inductance decreases by a factor of two. D The self-inductance increases by a factor of four.
10 Four long straight parallel wires carry equal currents directed vertically out of the page. They are arranged on the corners of a square as shown in the figure below
The direction of the resultant magnetic force exerted on the wire labelled X is A. south. B. north. C. west. D. east.
11 In the above figure, a wire and a 10 ohm resistor are used to form a circuit in the shape of a square, 20 cm by 20 cm. A uniform but non-steady magnetic field is directed into the plane of the circuit. The magnitude of the magnetic field is decreased from 0.60 T to 0.20 T in a time interval of 45 ms. The average induced current and its direction through the resistor, in this time interval, are closest to:
5
A
36 mA, from b to a
B
21 mA, from b to a
C
36 mA, from a to b
D
21 mA, from a to b
12 An a.c. supply is connected to a resistor. When the peak value of the e.m.f. of the supply is Vo and the frequency is f, the main power dissipated in the resistor in P. The supply frequency is then changed to 2f, the peak value of the e.m.f. remaining as Vo. What is now the mean power in the resistor? A P B C 2P D 4P
13 Two concentric rings X and Y are placed on the horizontal plane, as shown in the diagram below.
N Y X r1
r2 I 4I
The radius of ring X is r1= 1.0 m and r2 = 2.0 m. The current flows in ring Y is four times the current in ring X but in the opposite direction. The resultant magnetic flux density at the centre of the rings is A 1.5o I and points towards N
B 0.5o I and points towards N
C 0.5 o I and points towards S
D 1.5o I and points towards S
6
14 The table below shows the values of the resistance, capacitive reactance and inductive reactance for five RCL circuits. In which circuit will the voltage lead the current?
Resistance
Capacitive reactance
Inductive reactance
A 30 Ω
219 Ω
180 Ω
B 50 Ω
288 Ω
244 Ω
C 120
58
18
D 150 Ω
79 Ω
212 Ω
15 A variable capacitor is connected to an ac source. What effect does decreasing the capacitance have on the reactance and current in this circuit?
Reactance
Current
A
decreases
no change
B
increases
increases
C
decreases
increases
D
increases
decreases
7
SECTION B [15 Marks] Answer all questions in this section
16. Two metal spheres X and Y which are far apart are joined by a wire. The radius of sphere X is r1 and that of sphere Y is r2 . The charge densities on the surface of the sphere X and Y are 1 and 2 respectively. (a) Find, in terms of 1 and 2 (i) the ratio of the electric field intensity on the surface of sphere to that on the surface of sphere Y.
[3 Marks]
(ii) the ratio of the electric potential the surface of X to that of Y.
[1 Mark]
(b) Hence find the ratio of
1 , in terms of r1 and r2 . 2
[2 Mark]
8
17 (a) Define self-inductance .
[2 marks]
(b) A constant e.m.f. of 1.04 V is induced by a changing current in a coil of inductance 0.26H. The initial current is 13.0 A. Calculate, after 2.0 s of supplying the current, (i) the current in the coil, [3 marks]
(ii) the magnetic flux linkage in the coil. [2 marks]
9
Section C [30 Marks] Answer two questions only in this section
18. An alternating voltage is represented by V = 2.0 sin 314t (a) What is (i) the frequency
[1 mark]
(ii) the r.m.s. voltage for this a.c.?
[2 marks]
(b) The a.c. referred to in (a) is connected to a pure inductor of 5 mH. (i) Explain why this inductor produces an e.m.f. which opposes the supply voltage. [2 Marks] (ii) At a particular instant the supply voltage is 1.0 V What is the back e.m.f. in the inductor at that instant? [1 Mark] (iii) What is the r.m.s. current that flows in this inductor? [2 Marks]
(c)
(i) Sketch a graph to show the variation of voltage across the inductor with time. On the same axes, sketch the graph of the variation of current in the inductor with time. [3 Marks] (ii) Based on the graph in (c)(i), explain why the average power supplied to the inductor is zero. [3 Marks]
19 (a) An electric iron is labelled 240 V; 1.2 kW What do you understand by the labelling? [2 marks] (b)
(i) Define drift velocity.
[2 marks]
(ii) Copper has a molar mass of 63.5 10 3 kg and a density of 8900 kg m 3 . Assuming that each copper atom contribute one free electron, calculate the drift velocity of the electrons in a copper wire of radius 1.0 mm carrying a current of 0.15A. [6 marks]
10
(c) A copper conducting rod carries a current of 15.0 A. The cross-sectional area of the copper rod is a square of side 4.0 mm and its length is 60 m. Copper has a resistivity of 1.69x 10-8 Ω m. Calculate (i) the density of the current in the copper rod,
[3 marks]
(ii) the resistance of the copper rod.
[2 marks]
20. (a) Explain the meaning of the Hall effect. Describe a simple experiment to demonstrate the Hall effect. [5 Marks] (b) The figure shows a conductor where the majority of the charge carriers are free electrons of charge e and volume density n. The dimensions of the conductor are as shown. The conductor carries a current I and is in a magnetic field of flux density B.
(i) Derive an expression for the Hall voltage produced in a conductor in terms of the quantities mentioned above. [4 Marks] (ii) State the polarities of the Hall voltage. [2 Marks]
(iii) What information may be deduced from the magnitude and direction of the Hall voltage produced in a conductor? [4 Marks]
11
Values of constants (Nilai Pemalar) Acceleration of free fall
(Pecutan jatuh bebas)
g
= 9.81 m s-2
Avogadro constant
(Pemalar Avogadro)
NA
= 6.02 x 1023 mol-1
Boltzmann constant
(Pemalar Boltzmann)
k, kB = 1.38 x 10-23 J K-1
Gravitational constant
(Pemalar graviti)
G
= 6.67 x 10-11 N m2 kg-2
Magnitude of electronic
(Magnitud cas elektron)
e
= 1.60 x 10-19 C
Mass of the Earth
(Jisim Bumi)
ME
= 5.97 x 1024 kg
Mass of the Sun
(Jisim Matahari)
MS = 1.99 x 1030 kg
Molar gas constant
(Pemalar gas molar)
R
= 8.31 J K-1 mol-1
Permeability of free space
(Ketelapan ruang bebas)
0
= 4 x 10-7 H m-1
Permittivity of free space
(Ketelusan ruang bebas)
0
= 8.85 x 10-12 F m-1
charge
= (
)
Planck’s constant
(Pemalar Planck)
h
= 6.63 x 10-34 J s
Radius of the Earth
(Jejari Bumi)
RE
= 6.38 x 106 m
Radius of the Sun Rest mass
(Jejari Matahari)
RS = 6.96 x 108 m
of electron
(Jisim rehat elektron)
me
Rest mass of proton
(Jisim rehat proton)
mp = 1.67 x 10-27 kg
Speed of light in free space
(Laju cahaya dalam ruang bebas)
c
= 3.00 x 108 m s-1
Stefan-Boltzmann constant
(Pemalar Stefan-Boltzmann)
= 5.67 x 10-8 W m-2 K-4
Unified atomic mass unit
(Unit jisim atom bersatu)
u
= 1.66 x 10-27 kg
12
= 9.11 x 10-31 kg
