TJC 16 Circuits 2026

2026 Temasek Junior College 1 Unit 16: CIRCUITS Learning Outcomes Candidates should be able to: (a) recall and use appropriate circuit symbols. (b) draw and interpret circuit diagrams containing sources, switches, resistors (fixed and variable), ammeters, voltmeters, lamps, thermistors, light-dependent resistors, diodes, capacitors and any other type of component referred to in the syllabus. (c) define the resistance of a circuit component as the ratio of the potential difference across the component to the current in it, and solve problems using the equation V = IR (d) recall and solve problems using the equation relating resistance to resistivity, length and cross- sectional area, LR A = . (e) sketch and interpret the I – V characteristics of various electrical components in a d.c. circuit, such as an ohmic resistor, a semiconductor diode, a filament lamp and a negative temperature coefficient (NTC) thermistor. (f) explain the temperature dependance of the resistivity of typical metals (e.g. in a filament lamp) and semiconductors (e.g. in an NTC thermistor) in terms of the drift velocity and number density of charge carriers respectively. (g) show an understanding of the effects of the internal resistance of a source of e.m.f. on the terminal potential difference and output power. (h) solve problems using the formula for the combined resistance of two or more resistors in series. (i) solve problems using the formula for the combined resistance of two or more resistors in parallel. (j) solve problems involving series and parallel arrangements of resistors for one source of e.m.f including potential divider circuits which may involve NTC thermistors and light-dependent resistors. (k) solve problems using the formulae for the combined capacitance of two or more capacitors in series and in parallel. tutor copy

2026 Temasek Junior College 2 1 Electrical circuit symbols LO(a)(b) cell battery switch resistor variable resistor lamp / bulb d.c. power fuse thermistor LED ammeter voltmeter heater LDR diode junction (wires joined) 1.1 Practical Circuits Circuit diagrams are used to show how electrical components are connected together to perform useful tasks. The connecting wires (leads) are drawn as straight lines in the diagram. All circuits need at least one source of energy. A cell is a single component that transfers chemical energy to electrical energy. The longer line represents the positive terminal of a cell. When cells are connected together they are called a battery. cell bulb resistor V + − A V wire crossing (no connection) galvanometer earth

2026 Temasek Junior College 3 1.1.1 Measurement of potential difference 1.1.2 Measurement of current The p.d. is the difference in potential between two points. To measure t