Tutorial #4 — DC Circuits
Course: FAD1022 Basic Physics 2
Semester: 2 2025/2026
Week: Week #5 (26th - 30th January 2026)
Centre: Centre for Foundation Studies in Science, Universiti Malaya
Question 1
Two identical cells, each of e.m.f. 1.5 V and internal resistance $r$, are connected to three identical $6 \Omega$ resistors $R_1$, $R_2$, and $R_3$ (Figure 1).
If the ammeter reads 1.0 A, determine the magnitude of the:
a) equivalent resistance of the three resistors. b) internal resistance, $r$.
Question 2
When a cell (non-ideal emf) supplies 0.20 A, its terminal voltage is found to be 1.44 V. When the same cell supplies 0.60 A, its terminal voltage is 1.32 V.
Compute the cell's terminal voltage when it supplies 1.0 A.
Question 3
Based on circuit shown in Figure 3, calculate the potential difference between points A and B.
(Assume that internal resistance is negligible/the emf is ideal)
Question 4
This question is based on Figure 4 with resistors and voltage sources.
Circuit layout:
- 6Ω resistor (AB)
- 3Ω resistor (BC)
- 15 V source
- 12 V source
- 9Ω resistor (FE)
- Currents $I_1$, $I_2$, $I_3$ at junctions
- Loops L1 and L2
Write down the equations for:
a) Apply Kirchhoff Junction Rule (KJR) at node B for currents $I_1$, $I_2$, and $I_3$. b) Apply Kirchhoff Loop Rule (KLR) at Loop 1 (L1) for potential changes through FABEF. c) Apply Kirchhoff Loop Rule at Loop 2 (L2) for potential changes through BCDEB.
Question 5
Based on Figure 5 (similar to Figure 4):
Determine:
a) The magnitude for currents $I_1$, $I_2$, and $I_3$. b) Which current direction is wrongly chosen and state the correct direction.
Related Concepts
- AC Circuits
- Ohm's Law
- Kirchhoff's Current Law
- Kirchhoff's Voltage Law
- EMF
- Internal Resistance
- Terminal Voltage
- Resistor Network
- Series Circuit
- Parallel Circuit