Tutorial 13 — Electronics + Atomic Physics
Course: FAD1022 Basic Physics 2
Semester: 2 2025/2026
Centre: Centre for Foundation Studies in Science, Universiti Malaya (PASUM)
Question 1
Given the network Fig. 1, determine:
Circuit parameters:
- $V_{CC} = 16 \text{ V}$
- $R_B = 100 \text{ k}\Omega$
- $R_C = 8 \text{ k}\Omega$
- $R_E = 5 \text{ k}\Omega$
- $\beta = 80$
Calculate:
a) Whether approximate analysis can be used to analyze the network or not b) $V_B$ — ans: 1.185 V c) $I_C$ — ans: 0.097 mA d) $V_{CE}$ — ans: 14.545 V e) $I_C$ if $\beta$ changes to 100
Question 2
Determine the type of Op Amp, magnitude of the current passing through the 200 kΩ and amplitude of the output voltage for the circuit (Fig. 2), given the input voltage is:
a) 400 mV
- Current — ans: 100 μA
- Output voltage — ans: −20 V
b) 50 mV
- Current — ans: 0.0125 mA
- Output voltage — ans: −2.5 V
Question 3
Determine the amplitude of the output voltage for this circuit (Fig. 3), given the input voltage is 2 V and $R_f$ is six times bigger than the $R_1$.
Answer: 14 V
Question 4
Using the Bohr model of the hydrogen atom:
a) Derive an expression for the total energy of an electron in the $n$-th energy level. Show all necessary steps starting from fundamental principles.
b) Hence, show that the energy of the $n$-th level can be written as:
$$E_n = -13.6 \text{ eV} \left(\frac{1}{n^2}\right)$$
Question 5
An electron in a hydrogen atom undergoes a transition from the second excited state to the ground state.
Calculate the:
a) Energy of the photon emitted during this transition — ans: −12.1 eV b) Frequency of the emitted photon — ans: $2.92 \times 10^{15}$ Hz c) Identify spectral series to which transition belongs
Additional Question
Given $R_1 = 150 \text{ k}\Omega$, calculate value of feedback resistor if input voltage, $V_{in} = 1 \text{ V}$ is amplified to a magnitude of 10 V using a:
a) Non-inverting amplifier — ans: 1350 kΩ
b) Inverting amplifier — ans: 1500 kΩ
Related Concepts
- Transistors & Biasing
- Operational Amplifiers
- Atomic Physics
- BJT Analysis
- Voltage Divider Bias
- Operational Amplifier
- Op-Amp
- Inverting Amplifier ($A_v = -\frac{R_f}{R_1}$)
- Non-Inverting Amplifier ($A_v = 1 + \frac{R_f}{R_1}$)
- Bohr Model
- Hydrogen Atom
- Energy Levels
- Electron Transition
- Photon Emission
- Rydberg Formula
- Spectral Series