Electromagnetic Spectrum and Its Uses

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Electromagnetic Spectrum and Its Uses — Free MYP5 Physics Practice Questions

1QuestionOrder and Properties of EM WavesConcept Practice

3 marks~5 minCriterion A

A hospital imaging department uses four types of electromagnetic wave. Their frequencies are listed below.

Wave type	Frequency (Hz)
Radio	$1 \times 10^{8}$
Microwave	$1 \times 10^{10}$
Visible light	$5 \times 10^{14}$
X-ray	$1 \times 10^{18}$

The speed of light is

c = 3 \times 10^{8}

m s

^{-1}

State the four wave types in order of increasing frequency. [1]

Deduce the wavelength of the X-ray, and explain how the equation

c = f\lambda

shows that frequency and wavelength are inversely proportional for all electromagnetic waves. [2]

Solutions

2QuestionComparing EM Waves Speed Wavelength FrequencyAssessment Practice

3 marks~5 minCriterion A

Astronomers use electromagnetic waves to study the universe. The table below gives the wavelength of three electromagnetic waves in a vacuum.

Wave type	Wavelength
Radio wave	$1.0$ m
Visible light	$5.0 \times 10^{-7}$ m
X-ray	$1.0 \times 10^{-10}$ m

The speed of all electromagnetic waves in a vacuum is

c = 3.0 \times 10^{8}

m/s.

Calculate the frequency of each wave using

c = f\lambda

. [1]

Rank the three waves from lowest to highest frequency, and deduce how wavelength and frequency are related for electromagnetic waves travelling at the same speed. [1]

A radio telescope detects a signal at

1.5 \times 10^{9}

Hz and an X-ray observatory detects a signal at

3.0 \times 10^{18}

Hz. Analyse why X-ray observatories must be placed in space while radio telescopes can operate on Earth's surface. [1]

Solutions

3QuestionComparing EM Waves Speed Wavelength FrequencyConcept Practice

4 marks~6 minCriterion A

A spectrometer in a solar observatory detects a light wave with a period of

T = 2.0 \times 10^{-15}

s. The speed of light is

c = 3.0 \times 10^{8}

m s

^{-1}

State the equation relating period

T

and frequency

f

. [1]

Show that the wavelength of this wave is

6.0 \times 10^{-7}

m. [2]

The observatory needs to classify this wave for its optical instruments. Evaluate whether this wave falls within the visible spectrum, using your result from (b) and the known visible range of 400 nm to 700 nm. [1]

Solutions

4QuestionOrder and Properties of EM WavesAssessment Practice

4 marks~6 minCriterion C

The table below shows five types of electromagnetic radiation, their frequencies, and the percentage that passes through Earth's atmosphere.

Type	Frequency (Hz)	Transmission (%)
Radio	$3 \times 10^{6}$	100
Infrared	$3 \times 10^{12}$	20
Visible	$5 \times 10^{14}$	80
Ultraviolet	$3 \times 10^{15}$	0
X-ray	$3 \times 10^{18}$	0

Identify the general pattern between frequency and atmospheric transmission shown in the table, and identify one anomaly in that pattern. [2]

X-rays have frequency

3 \times 10^{18}

Hz and gamma rays have frequency

3 \times 10^{20}

Hz. Using the relationship

E = hf

, justify which type is more likely to be absorbed by the atmosphere and explain the molecular process responsible. [2]

Solutions

5QuestionComparing EM Waves Speed Wavelength FrequencyAssessment Practice

8 marks~12 minCriterion D

A company plans to launch a constellation of 12,000 satellites to provide global internet access. Each satellite transmits signals at a frequency of 20 GHz. Radio astronomers use telescopes that detect radio waves with wavelengths as short as 1 cm to study cosmic phenomena. The speed of electromagnetic waves in a vacuum is

c = 3.0 \times 10^8

m/s.

Calculate the wavelength of the satellite transmission signal. [2]

Deduce, using your answer to part (a), whether the satellite signals could interfere with radio telescope observations. [2]

Evaluate the ethical and environmental implications of deploying this satellite constellation. In your response, discuss: the benefits of global internet access; the impact on astronomical research; the limitations of using the wave equation alone to predict real-world interference; and a justified recommendation for balancing the competing interests. [4]

Solutions

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