# Circuit Components and Units & Prefixes

### Overview

Circuit symbols are considered as an introduction - it is not necessary to learn them all at this point. The aim of the lesson is to make the range of circuit symbols familiar and have a go at using some of the common ones to draw simple series and parallel circuits. The second part of the lesson considers all the different "units" that may be encountered. The actual units are relatively simple but the lesson concentrates on using the different exponents or prefixes (powers of 10) correctly.

### Learning Objectives

• Draw, communicate and analyse circuits using standard circuit symbols using standard convention
• Recognise, carry out calculations and be able to communicate using the following SI units: ampere (A), second (s), hertz (Hz), joule (J), watt (W), volt (V), ohm (Ω)
• Recognise and use expressions in standard form. For example, use frequencies expressed in standard form such as 2.5 × 107 Hz
• Recognise, carry out calculations and be able to communicate using the following SI multipliers: p, n, µ, m, k, M, G, T
• Recognise and use expressions in decimal form and convert between units with different prefixes, e.g. A to mA

### Lesson Content

Reading: The "components" webpage gives all the circuit symbols for electronic components that you are likely to meet when designing and building circuits. Work through the list of symbols and see how many you recognise. The aim of the reading is to become more familiar with the various symbols and not to learn them all. Eventually, with more experience, it is likely that you will know all of the symbols but you can always come back to look them up again.

Exercise: Complete the simple design exercises. Draw your circuits on paper using the components webpage and your knowledge of series and parallel circuits to help you. Check your circuit designs with the answers provided.

Reading: There are many different types of switches and they are often used in projects. The "switches" webpage gives an overview of the switches most commonly found in the electronics lab and most likely to be used in projects.

Reading: Reading about units and prefixes aims to develop some familiarity with the concepts that will be encountered later in the course. Learn the order of the prefixes as this is very useful later on. Work through each example carefully.

Video: Two worked examples involving the use of prefixes and standard form. The video uses the resistor equation as an example but it is not necessary to know this equation to understand the video, it is about how to use prefixes and standard form, not about how to use the resistor equation.

### Lesson Review

Review your learning by working through the presentations or notes which summarise the website content.

Presentation: Powerpoint download. Units and prefixes with lots of examples and questions.

Notes: PDF download. Units & Prefixes as a PDF document which is a useful quick reference guide.

### Self Assessment

Complete either the questions (pdf download) OR the on-line quiz. They are the same questions.

Quiz: On-line Circuit Components quiz. 8 questions that can be repeated as many times as required.

Quiz: On-line Units & Prefixes quiz. 10 questions that can be repeated as many times as required.

### Self Evaluation

I can:

• Recall the quantities and units applicable to simple circuits: Current, Voltage, Resistance and Charge
• Recall the quantities and units used for Energy and Power
• Recall the quantities and units used with time dependent circuits: Frequency, Time and Capacitance

• Change small values into standard units e.g. convert mA to A
• Change standard units into more convenient numbers using prefixes for small numbers e.g. A to mA
• Change large values into standard units e.g. convert kΩ into Ω
• Change standard units into more convenient numbers using prefixes for large numbers e.g. Ω to kΩ

• Use standard form with large values e.g. MHz expressed as x106 Hz
• Use standard form with small values e.g. µF expressed as x10-6 F