P4.2 The electromagnetic spectrum
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P4.2 The electromagnetic spectrum
Assessable content statements:
P4.2a recall that electromagnetic waves are transverse and are transmitted through space where they all have the same velocity
P4.2b explain that electromagnetic waves transfer energy from source to absorber
P4.2c apply the relationships between frequency and wavelength across the electromagnetic spectrum (M1a, M1c, M3c)
P4.2d describe the main groupings of the electromagnetic spectrum and that these groupings range from long to short wavelengths and from low to high frequencies
P4.2e describe that our eyes can only detect a limited range of the electromagnetic spectrum
P4.2f recall that light is an electromagnetic wave
P4.2g give examples of some practical uses of electromagnetic waves in the radio, micro-wave, infra-red, visible, ultra-violet, X-ray and gamma-ray regions
P4.2h describe how ultra-violet waves, X-rays and gamma rays can have hazardous effects, notably on human bodily tissues
P4.2i recall that radio waves can be produced by, or can themselves induce, oscillations in electrical circuits
P4.2j recall that different substances may absorb, transmit, refract, or reflect electromagnetic waves in ways that vary with wavelength
P4.2k explain how some effects are related to differences in the velocity of electromagnetic waves in different substances
The electromagnetic spectrum can be taught as an extension of light. Once learners see an illustration of the spectrum they can start to make links between the characteristics of light and the rest of the spectrum. It is important that learners understand that visible light is part of the EM spectrum, even though previously taught in isolation. Sound is not part of the EM spectrum.
Learners will have come across some of the other types of waves before: microwaves, X-rays, Gamma rays, radio waves and so a task to measure what learners already know will highlight misconceptions as well as illustrate previously gained knowledge.
When discussing the behaviour of the EM spectrum, it important to revisit how light behaves. The EM spectrum is governed by the same laws as light.
The use of diagrams, card sorts and cut and stick activates are a great way to engage learners in learning about the different groups of the EM spectrum. Learners will get to know how frequency and behaviour and use of a group are related. A useful way to encourage learners to learn about each group of the spectrum is for learners to research a particular group and then team teach it to the rest of the class. See details in activity section.
Common misconceptions or difficulties learners may have
Learners may confuse differences between the parts of the spectrum with differences in velocity. According to the equation velocity = frequency x wavelength learners may assume that the speed of the EM spectrum changes because the frequencies and wavelengths do. In fact the speed of the EM spectrum stays constant; the frequency and wavelength of each part of the spectrum is inversely proportional. As wavelength decreases, frequency increases and vice versa.
Electromagnetic spectrum is not related to electro-magnets, which learners may have previously studied.
The term radiation is often used interchangeably. Be sure to clarify that whilst all parts are known as radiation, only the high energy groups are examples of ionizing radiation.
Approaches to teaching the content
Learners will have experienced many of the groups of the EM spectrum: from radio waves, microwaves to UV rays and X rays. Asking learners to bring in any X rays they have, or if the teacher has any will help to engage the learners.
Explaining how Bluetooth or airdrop works on mobile phones (through the use of radio waves). If mobile phones are allowed in the classroom this could be used to send a file from a volunteer’s phone to the rest of the class to demonstrate how science is evident in everyday life.
Fibre optics is a great way to illustrate how the reflection of light can be used to develop new surgery tools. Many learners will know someone who has experiences keyhole surgery.
Learners may have previous experience of infrared when studying KS3 Heating and Cooling. Learners can interpret infrared images, and understand how police use infrared cameras.
Often a delicate topic but some learners/staff may know people who have had cancer treatment via gamma rays.
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