Electromagnetic Spectrum and Its Uses

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Electromagnetic Spectrum and Its Uses — Free MYP4 Physics Practice Questions

1QuestionOrder and Properties of EM WavesConcept Practice

2 marks~3 minCriterion A

Emergency services such as police and ambulance crews rely on radio wave communication to coordinate responses in real time.

Identify one property of radio waves that makes them suitable for this communication application. [1]

A paramedic crew reports that radio communication fails when their vehicle enters a long road tunnel. Explain, using the wave properties of radio waves, why signal loss occurs in this situation. [1]

Solutions

2QuestionOrder and Properties of EM WavesAssessment Practice

4 marks~6 minCriterion C

A student measures the frequency and wavelength of five electromagnetic waves travelling in a vacuum. The results are recorded below.

Wave A	frequency $= 3.0 \times 10^{9}$ Hz	wavelength $= 0.10$ m
Wave B	frequency $= 6.0 \times 10^{14}$ Hz	wavelength $= 5.0 \times 10^{-7}$ m
Wave C	frequency $= ?$	wavelength $= 4.0 \times 10^{-7}$ m
Wave D	frequency $= 1.0 \times 10^{18}$ Hz	wavelength $= 3.0 \times 10^{-10}$ m
Wave E	frequency $= 3.0 \times 10^{19}$ Hz	wavelength $= 1.0 \times 10^{-11}$ m

Deduce the frequency of wave C. [2]

Identify which region of the electromagnetic spectrum wave C belongs to, and justify your answer using its wavelength. [1]

A communications engineer claims that radio waves travel more slowly than gamma rays in a vacuum because radio waves carry less energy. Evaluate this claim using evidence from the data table. [1]

Solutions

3QuestionComparing EM Waves Speed Wavelength FrequencyConcept Practice

3 marks~5 minCriterion C

The electromagnetic spectrum spans frequencies from approximately

10^{4}

Hz (radio waves) to

10^{20}

Hz (gamma rays), yet all regions travel at

c = 3 \times 10^{8}

m/s in a vacuum.

State the value of the speed of all electromagnetic waves in a vacuum and identify what type of property this represents. [1]

Using the wave equation

v = f\lambda

, explain how wavelength must change as frequency increases, given that wave speed remains constant. [1]

A student claims: "Higher-frequency gamma rays must travel faster than radio waves because they carry more energy." Evaluate this claim using your understanding of electromagnetic wave behaviour in a vacuum. [1]

Solutions

4QuestionOrder and Properties of EM WavesAssessment Practice

6 marks~9 minCriterion A

A hospital uses X-rays to diagnose bone fractures and MRI (Magnetic Resonance Imaging) to image soft tissues such as the brain and muscles. X-rays are ionizing radiation with frequencies around

10^{18}

Hz. MRI uses non-ionizing radio waves and detects signals from hydrogen nuclei in water molecules within body tissues.

State one physical property of X-rays that makes them suitable for imaging bones, and state one risk associated with their use. [2]

Explain why MRI is considered safer than X-rays, and explain one reason why MRI is not always chosen as the first imaging method. [2]

Discuss the limitation of MRI for diagnosing bone fractures, linking your answer to the physics principle by which MRI produces an image. [2]

Solutions

5QuestionOrder and Properties of EM WavesAssessment Practice

10 marks~15 minCriterion D

A student investigates how the energy of electromagnetic (EM) waves depends on their frequency. The table below shows data for four types of EM radiation.

EM wave type	Frequency (Hz)	Energy per photon (J)
Radio	$1 \times 10^{8}$	$6.6 \times 10^{-26}$
Infrared	$3 \times 10^{12}$	$2.0 \times 10^{-21}$
Visible light	$6 \times 10^{14}$	$4.0 \times 10^{-19}$
Ultraviolet	$1 \times 10^{15}$	$6.6 \times 10^{-19}$

Planck's constant:

h = 6.6 \times 10^{-34}

J s

State the independent variable and the dependent variable in this investigation. [2]

Deduce the relationship between frequency and energy per photon using values from the table. [2]

Calculate the energy per photon of an EM wave with a frequency of

2 \times 10^{15}

Hz. Show your working. [2]

A medical imaging team argues that a higher-frequency EM wave is always more harmful to human tissue than a lower-frequency one. Evaluate this claim, using your knowledge of EM wave properties and at least one factor beyond frequency. [4]

Solutions

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