Lesson 8: Electromagnets in everyday devices
Stage/Year: Stage 3, Year 6
Time: 1 hour
Objective: For students to develop their understanding about the use of electromagnets by
disassembling everyday objects.
Syllabus Links:
Resources: [Class of 30]
SC4-10PW (NSW BOS, 2012a)
• Old blenders (x2)
• Old loud speakers (x4)
• investigate how magnets and electromagnets are used in
• Old doorbells (x4)
some everyday devices or technologies used in everyday
• Screw drivers (Flat head x 5
life (p.107)
and phillips head x5)
ST3-6PW (NSW BOS, 2012a)
• Hammer (x1)
• identify potential risks and demonstrate safe use when
• Prezi presentation
using electrical circuits and devices (p.66)
“Electromagnet Stage 3 Year
ST3-5WT (NSW BOS, 2012a)
6” (link located at the bottom
• selecting and safely using a range of tools, equipment and
of this webpage)
related techniques to cut, edit, join, manipulate and shape
• 8 computers/laptops/iPads
materials and/or information (p.64)
(with internet connection)
ST3-4WS (NSW BOS, 2012a)
• with guidance, posing questions to clarify practical problems
or inform a scientific investigation (p.62)
• working collaboratively in conducting a range of appropriate
investigation methods, including fair tests, to answer
questions or solve problems (p.62)
• using equipment and materials safely, identifying potential
risks (p.62)
EN3-1A (NSW BOS, 2012b)
• participate in and contribute to discussions, clarifying and
interrogating ideas, developing and supporting arguments,
sharing and evaluating information, experiences and
opinions (p.98)
EN3-3A (NSW BOS, 2012b)
• identify and explain how analytical images like figures,
tables, diagrams, maps and graphs contribute to our
understanding of verbal information in factual texts (p.103)
• select, navigate and read texts for a range of purposes,
applying appropriate text processing strategies and
interpreting structural features (p.103)
Summary table of KSK:
• An electromagnet needs insulated copper wire, a battery source and an iron core (BBC, 2013;
Johnson, Adamson & Williams, 2000).
• Devices that use electromagnets include, an electric bell, an electric lock, eye surgeon
equipment to remove metal from the eye, blenders, mobile phones, fans, speakers, tape
recorders, doorbells, motors and industrial lifting equipment, such as crane (Department of
Electrical, Computer, and Energy Engineering, 2012; Hoadley, 2013; Rubin, 2013; School
science, 2013).
• Speakers contain an electromagnet that consists of single coil layer that can move but is fixed
to a paper cone at the center of the speaker and is surrounded by a permanent circular magnet
(Hoadley, 2013; UNSW School of Physics, 2013). However, some speakers are solenoid as
they do not use an iron core (Hoadley, 2013; UNSW School of Physics, 2013). The amount of
current running through the wire will influence the rate of movement of the electromagnet and
cone, for example, the faster the current, the higher the frequencies and the faster the cone
and electromagnet moves (Hoadley, 2013). The larger the movement of cone and
electromagnet, the louder the sound (Hoadley, 2013).
• Doorbell also uses an electromagnet, in particular a solenoid piston. ‘When there is no electric
current, the iron core is not directly in the middle of the solenoid. When an electric current is
produced (when the doorbell button is pressed), the iron core inside becomes attracted to the
magnetic field created by the solenoid and moves forward in order for the solenoid to be
directly in middle of the iron core. By doing this, the end of the iron core hits against a tone-bar.
When the current stops, the spring attached on the opposite end of the tone-bar pushes the
iron core back to its original position’ (Harris, 2003).
Lesson Overview:
Introduction (10 minutes)
• As a whole class, recap the previous lesson. Ask students:
1. What is an electromagnet?
2. What is a solenoid?
3. What components are needed in an electromagnet?
4. How does an electromagnet work?
• Encourage a student to draw an electromagnet on the IWB.
Body (Rotating groups - 20 minutes each station)
• As a whole class, discuss safety issues (for example, appropriate use of tools and behaviors)
GROUP 1 (adapted from Hoadley, 2013).
• In groups of 4, students will use the appropriate tools to disassemble devices that contain
electromagnets. After students disable the device, students will need to identify the
components in an electromagnet. Students will also need to decide whether it is an
electromagnet or a solenoid. Students will discuss with each other how they think the
electromagnet works in this device.
GROUP 2
• In pairs, students will use the Prezi link (http://prezi.com/q9iksmcdeegt/electromagnet-stage-3year-6/) to explore electromagnets. Students will watch and play the relevant videos and
games and answer relevant questions about various aspects of electromagnets.
Conclusion (10 minutes)
• As a whole class, encourage students to discuss what they learnt or found interesting about
electromagnets. Encourage students to discuss the way the electromagnets were in the
devices, for example, were there more solenoid or electromagnets?.
Simplification: Pair based on ability in order to Extension: Encourage students to discuss how
scaffold learning and provide assistance as
they think the magnetic field could be created in
appropriately needed by students.
the device.
Additional Learning Opportunities:
• Encourage students to explore and research devices that use electromagnets. From here,
encourage students to create their own Prezi and present it to the class about how an
electromagnet works in a specific device they researched.
This lesson developed by Sarah Lindsay (42019370)