FAD1022 UAS 2023-2024

Basic Physics II Final Examination for 2023/2024 Semester 2. Source file: UAS 23-24 FAD1022 Basic Physics II from /home/kuumin/docs/nothingburger/wiki/assets/uas/

Exam Information

  • Course: FAD1022 - Basic Physics II
  • Academic Year: 2023/2024
  • Semester: 2
  • Duration: 3 hours
  • Total Pages: 24 printed pages
  • Format:
    • Section A: 15 questions (ALL must be answered) - 45 marks
    • Section B: 5 questions (answer ANY 3) - 36 marks
    • Section C: 6 questions (answer ANY 4) - 48 marks
  • Total Marks: 129 marks

Constants Provided

Constant Symbol Value
Planck's constant $h$ $6.63 \times 10^{-34}$ J s
Reduced Planck's constant / Dirac constant $\hbar$ $1.05 \times 10^{-34}$ J s
Speed of light $c$ $3.0 \times 10^{8}$ m s$^{-1}$
Coulomb's constant $k$ $9.0 \times 10^{9}$ N m$^2$ C$^{-2}$
Permittivity of free space $\varepsilon_0$ $8.85 \times 10^{-12}$ C$^2$ N$^{-1}$ m$^{-2}$
Permeability of free space $\mu_0$ $4\pi \times 10^{-7}$ T m A$^{-1}$
Mass of electron $m_e$ $9.1 \times 10^{-31}$ kg
Elementary charge $e$ $1.6 \times 10^{-19}$ C

Conversions:

  • $1 \text{ eV} = 1.602 \times 10^{-19}$ J
  • $1 \text{ u} = 931.5$ MeV c$^{-2}$

Topic Distribution

Topic Questions Approx. Marks Percentage
Electrostatics A1, A2, A3, B1, B2 ~27 21%
DC Circuits A4, B3 ~10 8%
AC Circuits A5, A6, B4, B5 ~21 16%
Magnetism A7, A8, C1 ~15 12%
Electromagnetic Induction A9, A10, A11, C2, C3 ~27 21%
Semiconductors & Electronics A12, A13, C4 ~15 12%
Atomic Physics A14 ~3 2%
Nuclear Physics C5 ~12 9%
Modern Physics / Wave-Particle Duality A15, C6 ~9 7%

Section A — Answer ALL Questions

Question A1

  • Topic: Electric Field Lines
  • Concepts: Electrostatics, Electric Field
  • Question: Figure A1 shows an electric field across three regions, labelled X, Y, and Z. Determine in which region the electric field is:
    • (a) strongest [1 mark]
    • (b) weakest [1 mark]
    • (c) most uniform [1 mark]
  • Diagram: Three regions (X, Y, Z) with electric field lines passing through. Region X has parallel lines, region Y has converging lines, region Z has diverging lines.

Question A2

  • Topic: Electric Flux
  • Concepts: Electric Flux, Gauss's Law
  • Question: A uniform electric field passes through a disk with a radius of 0.15 m, resulting in an electric flux of 282 N m$^2$ C$^{-1}$. Calculate the electric field strength when the disk's surface is inclined at 30° to the direction of the electric field. [3 marks]
  • Formula: $\Phi_E = EA\cos\theta$

Question A3

  • Topic: Capacitor Energy
  • Concepts: Capacitors & Dielectrics, Electric Potential Energy
  • Question: A heart defibrillator delivers 150 J of energy by discharging a capacitor initially at 400 V. Calculate the charge stored by the capacitor. [3 marks]
  • Formula: $U = \frac{1}{2}QV = \frac{1}{2}CV^2$

Question A4

  • Topic: EMF and Internal Resistance
  • Concepts: EMF and Internal Resistance, Ohm's Law
  • Question: Calculate the current flowing through a 5.0 Ω resistor when it is connected to a battery having terminal voltage of 6.3 V and internal resistance of 0.25 Ω. [3 marks]
  • Formula: $I = \frac{V_{terminal}}{R_{load}}$ or using $\mathcal{E} = V_{terminal} + Ir$

Question A5

  • Topic: Inductive Reactance
  • Concepts: Inductance & Transformers, AC Circuits
  • Question: An inductor has inductance $L$ and reactance $X_L$. If the new inductance and frequency are three times the original ones, determine the new reactance in terms of $X_L$. [3 marks]
  • Formula: $X_L = 2\pi f L$

Question A6

  • Topic: RL Series Circuit
  • Concepts: AC Series Circuits, RL Circuits
  • Question: An RL series circuit consists of 10 kΩ resistance and 1000 Ω reactive inductance. If the voltage across the resistor is 20 V, calculate the voltage across the inductor. [3 marks]
  • Key concept: In RL circuits, $\frac{V_L}{V_R} = \frac{X_L}{R}$

Question A7

  • Topic: Ampere's Law & Magnetic Torque
  • Concepts: Magnetism, Ampere's Law, Magnetic Torque
  • Question:
    • (a) Based on Figure A7 (a), identify Amperian path $dl$ that results in a zero magnetic field and justify your answer. [1 mark]
    • (b) Explain briefly how the orientation of a conductive loop affects the magnetic torque it experiences when placed in a uniform magnetic field. [2 marks]
  • Diagram: Rectangular loop with current-carrying wires and magnetic field $\vec{B}$ directed rightward. Four paths labeled a, b, c, d forming the loop.

Question A8

  • Topic: Velocity Selector (Lorentz Force)
  • Concepts: Magnetism, Lorentz Force, Charged Particle Motion
  • Question: An electron moves across a velocity selector. Calculate the velocity $v$ of the electron if the electron experiences no deflection due to the electric field of 280 kV m$^{-1}$ and the magnetic field of 25 mT. [3 marks]
  • Formula: $v = \frac{E}{B}$ (for no deflection)
  • Diagram: Two parallel plates with opposite charges creating electric field $\vec{E}$ downward, magnetic field $\vec{B}$ into the page, electron entering with velocity $v$.

Question A9

  • Topic: Lenz's Law
  • Concepts: Faraday's Law, Lenz's Law, Electromagnetic Induction
  • Question: A solenoid is approaching a magnetic bar (Figure A9). Explain what will happen to the solenoid according to Lenz's Law. [3 marks]
  • Diagram: Solenoid connected to galvanometer with ends A and B, bar magnet with N pole approaching the solenoid.

Question A10

  • Topic: Motional EMF
  • Concepts: Electromagnetic Induction, Motional EMF
  • Question: An airplane has a wingspan of 30.0 m and flies at a constant altitude in a northerly direction with a speed of 240 m s$^{-1}$. If the vertical component of the earth's magnetic field is $5.0 \times 10^{-6}$ T, and its horizontal component is $1.4 \times 10^{-6}$ T, calculate the induced emf between the wingspans. [3 marks]
  • Formula: $\varepsilon = Blv$ (use vertical component of B, as motion is horizontal)

Question A11

  • Topic: Mutual Inductance
  • Concepts: Mutual Inductance, Inductance & Transformers
  • Question: Coils P and S with 11 and 16 turns respectively, are placed near one another. A current of 2.0 A flows through coil P, inducing a magnetic flux of 0.04 Wb in coil S. Calculate the mutual inductance of coil S. [3 marks]
  • Formula: $M = \frac{N_S \Phi_S}{I_P}$

Question A12

  • Topic: Diodes & Rectification
  • Concepts: Semiconductors & Diodes, Rectification
  • Question:
    • (a) Based on your understanding about diode, give ONE reason why current does not flow in a circuit consisting of a resistor, a diode and a DC power supply connected in series. [1 mark]
    • (b) A circuit consists of an AC power supply, a resistor and a diode are connected in series. Sketch the output waveforms across the:
      • (i) resistor [1 mark]
      • (ii) diode [1 mark]

Question A13

  • Topic: Transistor Biasing
  • Concepts: Transistors & Biasing, BJT
  • Question: An emitter-stabilized bias transistor network has $V_{CC} = 20$ V and $R_E = 1$ kΩ. Given $I_B = 30$ μA and $\beta = 120$, calculate $R_B$. [3 marks]
  • Formula: Using KVL: $V_{CC} = I_B R_B + V_{BE} + I_E R_E$, where $I_E = (\beta + 1)I_B$

Question A14

  • Topic: Bohr Model / Atomic Energy Levels
  • Concepts: Atomic Physics, Bohr Model
  • Question: A photon is released when a hydrogen atom moves from the fifth energy level to the third level. Determine the energy of the photon released in electron volts. [3 marks]
  • Formula: $E_n = -\frac{13.6}{n^2}$ eV, $\Delta E = E_5 - E_3$

Question A15

  • Topic: Photoelectric Effect
  • Concepts: Photoelectric Effect, Photons
  • Question: The photoelectric threshold wavelength of a tungsten surface is 272 nm. Calculate the maximum kinetic energy of the electrons ejected from this tungsten surface by ultraviolet radiation of frequency $1.45 \times 10^{15}$ Hz. Express your answer in electron volt. [3 marks]
  • Formula: $K_{max} = hf - \phi = hf - \frac{hc}{\lambda_0}$

Section B — Answer ANY THREE Questions

Question B1

  • Topic: Electrostatics — Coulomb's Law, Electric Field, Electric Potential
  • Concepts: Coulomb's Law, Electric Field, Electric Potential
  • Total Marks: 12 marks

(a) Redraw Figure B1 (a) and show the direction of resultant electric force on $q_2$. [2 marks]

  • Diagram: Equilateral triangle with charges: $q_1 = +2$ μC, $q_2 = +2$ μC, $q_3 = -2$ μC at vertices. Side length = 5 cm.

(b) Figure B1 (b) shows two charges, $q_1 = 2$ μC and $q_2 = -5$ μC. Calculate the magnitude of resultant electric field at point P. [6 marks]

  • Diagram: Right-angled triangle with $q_1$ at right angle vertex, $q_2$ 4 cm to the right. Point P is 3 cm above $q_1$, 5 cm from $q_2$.

(c) A point charge $q = 3$ μC is located at the origin as shown in Figure B1 (c). Calculate the:

  • (i) electric potential at point A and point B [3 marks]
  • (ii) electric potential difference between point A and B [1 mark]
  • Diagram: Charge $q$ at origin. Point A is 5 cm above (along y-axis), Point B is 4 cm to the right (along x-axis).

Question B2

(a) State TWO factors that can increase the capacitance of a parallel air-filled plate capacitor. [2 marks]

(b) Six capacitors of 13 μF each are connected as shown in Figure B2 (b). Calculate the equivalent capacitance. [4 marks]

  • Diagram: Complex capacitor network with capacitors C1 through C6 connected with a 500V battery.

(c) A parallel plate capacitor with an area of 18 cm$^2$ has a capacitance of 100 μF and a dielectric constant of 7.

  • (i) Determine the strength of the electric field formed, if a 12 V potential difference is applied across the capacitor. [5 marks]
  • (ii) Explain the changes in the strength of electric field if the gap between the plates is air. [1 mark]

Question B3

Figure B3 shows a Wheatstone bridge, an electrical measuring instrument used to measure an unknown resistance.

(a) Explain the working principle of a Wheatstone bridge. [2 marks]

(b) Derive an equation to determine value of the unknown resistance, $R_X$ in terms of $R_S$, $R_1$ and $R_2$. [6 marks]

(c) Determine the equivalent resistance of the circuit if $R_1 = 2.0$ Ω, $R_2 = 4.0$ Ω, $R_3 = 5.0$ Ω and $R_S = 3.0$ Ω. [4 marks]

  • Diagram: Classic Wheatstone bridge with resistors $R_1$, $R_2$, $R_X$, $R_S$ in a diamond configuration, galvanometer across the bridge, and $R_3$ in series with the supply.

Question B4

  • Topic: AC Circuits — Capacitive Reactance
  • Concepts: AC Circuits, Capacitive Reactance, Phasors
  • Total Marks: 12 marks

(a) Explain the relationship between capacitive reactance $X_C$ and frequency $f$, with the aid of suitable graph. [2 marks]

(b) Figure B4 (b) shows the voltage signal in an AC circuit connected across a 20 kΩ resistor. Determine the:

  • (i) rms voltage [2 marks]
  • (ii) rms current [2 marks]
  • Diagram: Sinusoidal voltage waveform with peak voltage 4.5 V and period shown (16 ms corresponds to one full cycle).

(c) Based on Figure B4 (c):

  • (i) write the complete equation of the current if the frequency is 60 Hz [4 marks]
  • (ii) determine the current at $t = 4$ ms [2 marks]
  • Diagram: Current waveform with amplitude 2 A and phase shift of $\pi/4$ shown.

Question B5

  • Topic: RLC Series Circuits
  • Concepts: AC Series Circuits, RLC Circuits, Resonance
  • Total Marks: 12 marks

(a) Explain TWO characteristics of an RLC series circuit when inductive reactance is equal to capacitive reactance. [2 marks]

(b) An RLC series circuit has resistance $R = 235$ Ω and inductive reactance $X_L = 175$ Ω. Calculate the circuit's capacitive reactance $X_C$ if its power factor is 0.707. [4 marks]

(c) An RLC series circuit which consists of a resistor, a 3 H inductor and a 3 mF capacitor is connected to an a.c source of 120 V$_{rms}$. The apparent power of the circuit is 480 W with a phase angle of zero. Calculate the:

  • (i) resistance of the resistor [4 marks]
  • (ii) current across the inductor [2 marks]

Section C — Answer ANY FOUR Questions

Question C1

  • Topic: Magnetism — Magnetic Field, Lorentz Force, Ampere's Law
  • Concepts: Magnetism, Lorentz Force, Ampere's Law
  • Total Marks: 12 marks

(a) A negative charge moves with velocity $v$ towards the current-carrying wire in the direction of the $-x$ axis, Figure C1 (a). At point P, determine the direction of the:

  • (i) magnetic field [1 mark]
  • (ii) magnetic force on the charge [1 mark]
  • Give your answer using the provided axes.
  • Diagram: Current-carrying wire with current to the left, negative charge moving downward toward the wire. Point P between charge and wire.

(b) A long wire with radius $R$ carries a current $I$.

  • (i) Using Ampere's law, show that the magnetic field $B$ inside a long wire is expressed as: $$B = \frac{\mu_0 I r}{2\pi R^2}$$ where $r$ denotes the radius of the Amperian path. [2 marks]
  • (ii) Calculate the magnetic field at a distance of 2.3 mm below the surface of the wire, with $R = 10$ mm and $I = 18$ A. [2 marks]

(c) A long straight wire with current $I_1$ is placed 1.5 cm away from a square loop wire with side length of 4.5 cm, Figure C1 (c). Calculate the current $I_2$, if the resultant magnetic force acting on the loop wire is $3.6 \times 10^{-6}$ N. [6 marks]

  • Diagram: Long straight wire with $I_1 = 2.0$ A (leftward) above a square loop. Distance from wire to top of loop = 1.5 cm. Loop side = 4.5 cm with current $I_2$.

Question C2

  • Topic: Electromagnetic Induction — DC Motor, Faraday's Law
  • Concepts: DC Motor, Faraday's Law, Electromagnetic Induction
  • Total Marks: 12 marks

(a) One of the problems in the rotation of rectangular conductor in motor is the direction of the force is still upward even after it reaches certain angles between 90° < $\theta$ < 180°. Suggest TWO methods to solve the direction of the force. [2 marks]

(b) A technician wearing a circular metal band on his wrist moves his hand into a uniform magnetic field of magnitude 2.5 T in 0.18 s. If the diameter of the band is 6.5 cm and magnetic field is at an angle of 55° with the plane of the metal band, calculate the average induced emf of the band. [4 marks]

(c) A straight conductor bar CD with length of 2.0 m and a resistance of 2.5 Ω are placed in a uniform magnetic field. The conductor is moved perpendicular to the magnetic field at a speed of 3.5 m s$^{-1}$, Figure C2 (c).

  • (i) Derive the equation of induced emf in the wire. [3 marks]
  • (ii) Determine the induced emf in the wire if the magnetic field is $3.0 \times 10^{-5}$ T. [2 marks]
  • (iii) Determine the direction of the induced current. [1 mark]
  • Diagram: Conductor bar CD moving rightward on rails with resistor R, magnetic field into page (× symbols). Velocity vector shown.

Question C3

  • Topic: Inductance & Transformers
  • Concepts: Inductance & Transformers, Self-Inductance, Mutual Inductance
  • Total Marks: 12 marks

(a) One of the applications of inductors is to store energy in the form of magnetic field. Suggest TWO ways to increase the value of energy stored in the inductor. [2 marks]

(b) A current in a 29 mH inductor decreases from 8.0 A to 3.5 A in 15 ms.

  • (i) Calculate the magnitude of induced emf in the inductor. [3 marks]
  • (ii) Determine the direction of induced current. [1 mark]

(c) A power efficient wireless charger operates at 20 V, 60 - 70 Hz can be used to charge various devices. If the ratio of coil turns of wireless charger to handphone is 4:1, calculate the:

  • (i) resistance in the handphone [4 marks]
  • (ii) current flow in the wireless charger [2 marks]

Question C4

  • Topic: Transistor Amplifiers
  • Concepts: Transistors & Biasing, BJT, Voltage Divider Bias
  • Total Marks: 12 marks

(a) Explain why the output current of a transistor may exhibit fluctuations and instability. [2 marks]

(b) Given $I_E = 5$ mA and $I_B = 40$ μA for a fixed-bias transistor network, determine $\beta$. [4 marks]

(c) Figure C4 (c) shows a transistor network.

  • (i) Determine $I_C$ using the approximate analysis approach. [5 marks]
  • (ii) Analyze stability of the output current $I_C$ if $\beta$ increases to 120. [1 mark]
  • Diagram: Voltage divider bias circuit with: $V_{CC} = 20$ V, $R_C = 5$ kΩ, $R_B1 = 100$ kΩ, $R_B2 = 10$ kΩ, $R_E = 2$ kΩ, $\beta = 90$

Question C5

  • Topic: Nuclear Physics — Radioactive Decay, Mass-Energy
  • Concepts: Nuclear Physics, Radioactive Decay, Binding Energy
  • Total Marks: 12 marks

(a) Radium-226, with atomic number of 88 produces radioactive gas radon-222, by alpha decay. Write an equation represents the decay process. [2 marks]

  • Decay: $^{226}{88}\text{Ra} \rightarrow {}^{222}{86}\text{Rn} + {}^4_2\alpha$

(b) $^{25}{13}\text{Al}$ will decay to $^{25}{12}\text{Mg}$. Given the atomic mass of $^{25}{12}\text{Mg}$ is 24.985837 u and atomic mass of $^{25}{13}\text{Al}$ is 24.990429 u. (mass of alpha, $\alpha = 4.001506$ u, mass of beta, $\beta = 0.000549$ u)

  • (i) Calculate the energy released during the process, in MeV. [3 marks]
  • (ii) State the type of the decay. [1 mark]

(c) The rate of decay for a radioactive sample is measured by a counter. The net count rate is $R$. Figure C5 (c) shows the graph of $\ln(R/s^{-1})$ against $t$.

  • (i) Determine the half-life of the radioactive nuclei in the sample. [4 marks]
  • (ii) Find the counts rate of the sample at $t = 0$ from the graph. [2 marks]
  • Diagram: Graph of $\ln(R)$ vs $t$ (hours) showing a straight line with negative slope. Initial value at $t=0$ is approximately $\ln(R) \approx 8.3$.

Question C6

(a) Explain "undetectably small" state in wave particle duality. [2 marks]

(b) A gamma ray photon has an energy of $7.32 \times 10^5$ eV. Determine its momentum. [4 marks]

  • Formula: $p = \frac{E}{c}$

(c) An electron is confined within a region of width $2.5 \times 10^{-10}$ m. Calculate the:

  • (i) minimum uncertainty estimation of the electron momentum in the x-component. [3 marks]
  • (ii) electron's kinetic energy if the electron has uncertainty momentum as calculated in (i). [3 marks]
  • Formula: $\Delta p \geq \frac{\hbar}{2\Delta x}$

Key Topics Tested

[!important] Comprehensive Coverage This exam covers the full spectrum of Basic Physics II:

Foundation (Electrostatics & DC): ~29 marks

  • Electric field concepts and calculations
  • Gauss's law applications
  • Capacitor energy and combinations
  • Wheatstone bridge analysis

AC Circuits: ~21 marks

  • Reactance and impedance
  • RLC series circuits and resonance
  • Phasor analysis
  • Power factor

Magnetism & Induction: ~42 marks

  • Ampere's law derivations
  • Lorentz force and velocity selector
  • Faraday's law applications
  • Mutual inductance and transformers
  • DC motor principles

Electronics: ~15 marks

  • Diode operation and rectification
  • Transistor biasing (fixed-bias and voltage divider)
  • Amplifier stability

Modern Physics: ~24 marks

  • Bohr model energy transitions
  • Photoelectric effect calculations
  • Nuclear decay and mass-energy equivalence
  • Wave-particle duality and Heisenberg uncertainty

Study Recommendations

  1. Master electrostatics fundamentals — Coulomb's law, electric field calculations, and potential difference are heavily tested
  2. Practice RLC circuit analysis — Know how to calculate impedance, power factor, and resonance conditions
  3. Understand electromagnetic induction — Be comfortable with Faraday's law, Lenz's law, and motional EMF
  4. Review transistor biasing — Both fixed-bias and voltage divider configurations appear frequently
  5. Know your nuclear physics — Radioactive decay equations, half-life calculations from graphs, and mass-energy equivalence

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Transcribed: 2026-05-04 Source: FAD1022 UAS 2023-2024 (24 pages)