The electromagnetic spectrum and risk

플레이하며 배우기

이 문제들을 풀어 에너지를 얻은 뒤 낚시하고 탐험하세요. 계정이 필요 없어요.

교육자를 위해: The electromagnetic spectrum and risk(MYP Physics, Year 4)을(를) 위한 바로 쓸 수 있는 수업 슬라이드, 복습 노트 — 수업에 사용하거나, 학습자들이 실시간 게임으로 즐기는 인터랙티브 클래스 활동으로 진행하세요.

수업 노트

Big idea: the electromagnetic spectrum and risk

Key concept: Relationships. All electromagnetic waves travel at the same speed in a vacuum. Higher frequency means shorter wavelength and greater photon energy.
Related concepts: Models and evidence. Use a scientific explanation to make predictions, then test it against observations.
Global context: Scientific and technical innovation. Different spectrum regions support communication, imaging and treatment.

Electromagnetic Waves

The electromagnetic spectrum is a continuous range of waves arranged by wavelength or frequency.
Longer wavelength → lower frequency; shorter wavelength → higher frequency.
Order from longest to shortest wavelength: radio waves, microwaves, infrared, visible light (ROYGBIV), ultraviolet, X-rays, gamma rays.
All EM waves are transverse waves that transfer energy.
All EM waves travel at the same speed in a vacuum: 3.0 × 10⁸ m/s (also approximately the speed in air).
Visible light is only a small part of the EM spectrum.

The electromagnetic spectrum, showing the seven regions in order of decreasing wavelength (increasing frequency), from radio waves to gamma rays.

Uses of Electromagnetic Waves

Radio waves: radio/TV transmissions, astronomy, RFID.
Microwaves: satellite TV, mobile phones, microwave ovens, WiFi.
Infrared: remote controls, thermal imaging, optical fibres, intruder alarms.
Visible light: vision, photography, illumination.
Ultraviolet: security marking, detecting fake bank notes, sterilising water, fluorescence.
X-rays: medical scanning, security scanners (absorbed by bone, pass through tissue).
Gamma rays: sterilising food/equipment, cancer detection and treatment.

Dangers of Electromagnetic Waves

Higher frequency EM waves carry more energy and can ionise atoms (UV, X-rays, gamma rays).
Microwaves: internal heating of body cells (water absorption).
Infrared: skin burns.
Ultraviolet: skin cancer, eye damage; protection via sunscreen and sunglasses.
X-rays and gamma rays: cell mutation, DNA damage, cancer; radiographers use lead screens.
Radiation risk depends on radiation type, absorbed dose, exposure and the tissue affected. Greater electromagnetic frequency increases photon energy but does not by itself determine risk.

Communications

Microwaves are used for satellite communication (mobile phones, satellite TV) because they are not absorbed/reflected by the atmosphere.
Radio waves diffract around hills (similar wavelength to obstacles), used for local radio and Bluetooth.
Optical fibres use visible light or infrared for high-speed broadband; high frequency allows high data rates.
Geostationary satellites: orbit at 36 000 km, period 24 h, used for broadcasting; longer time delay.
Low‑orbit/polar satellites: orbit at ~200 km, shorter delay, used for weather and imaging.

A satellite in geostationary orbit above the Earth's equator, showing communication signals to other parts of the world.

Digital & Analogue Signals

Analogue signals vary continuously and can take any value.
Digital signals have only two states (0/1, high/low).
Digital signals can be regenerated with minimal noise, giving larger range and higher data rate.
Extra data can be added to digital signals for error checking.
Digital sampling converts an analogue signal to digital by recording at set time intervals.

A digital signal, which can only take one of two states (0 or 1).

Think like a scientist

Analyse teacher-provided frequency and wavelength values for electromagnetic waves in a vacuum.
Comparison: the frequency of the radiation. Outcome: the corresponding wavelength.
Control: compare propagation in a vacuum. Explain why this makes the comparison fairer.
Evidence: Use a consistent method, repeated observations where appropriate and a table with labelled quantities and units. Keep unexpected results and investigate their cause.
Safety: Practical activities need teacher supervision and an appropriate risk assessment. Use the provided data or simulation where the investigation specifies it.
Inquiry task: State a testable question, predict the outcome using the science, then explain how your observations would support or challenge the prediction.

Evaluate the science

Different spectrum regions support communication, imaging and treatment.
Risk depends on type, dose and exposure; non-ionising radiation can still cause harm through heating or other interactions.
Evaluation task: Link your conclusion to evidence, identify a limitation and suggest a specific improvement. Distinguish a measured result from an explanation of its cause.

슬라이드

Step through every slide for this topic — plus flashcards and revision notes — with a free account.

가입 — 무료 로그인

연습 문제

무료 미리 보기 — 51개 중 8개 문제. 가입하면 전부 볼 수 있어요.

1.Which of the following lists the electromagnetic spectrum in order of decreasing wavelength?
Easy
- ARadio waves, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays
- BGamma rays, X-rays, ultraviolet, visible, infrared, microwaves, radio waves
- CRadio waves, infrared, microwaves, visible, ultraviolet, gamma rays, X-rays
- DVisible, infrared, radio waves, microwaves, ultraviolet, X-rays, gamma rays
2.All electromagnetic waves travel at the same speed in a vacuum. What is this speed?
Easy
- A3.0 × 10⁸ m/s
- B3.0 × 10⁶ m/s
- C3.0 × 10¹⁰ m/s
- D3.0 × 10³ m/s
3.Which type of electromagnetic radiation is used for television remote controls?
Easy
- AInfrared
- BRadio waves
- CUltraviolet
- DMicrowaves
4.Which of the following is a harmful effect of excessive exposure to ultraviolet radiation?
Easy
- ASkin cancer
- BInternal heating of body cells
- CSkin burns
- DMutation of DNA
5.Which type of electromagnetic radiation has a wavelength of about 1 km?
Easy
- ARadio waves
- BMicrowaves
- CInfrared
- DVisible light
6.A geostationary satellite orbits at a height of 36 000 km above the Earth's surface. What is its orbital period?
Easy
- A24 hours
- B12 hours
- C48 hours
- D72 hours
7.Which property increases as you move from radio waves to gamma rays in the electromagnetic spectrum?
Easy
- AFrequency
- BWavelength
- CSpeed in a vacuum
- DAmplitude
8.Which type of signal can only take one of two discrete values?
Easy
- ADigital signal
- BAnalogue signal
- CRadio signal
- DMicrowave signal

더 많은 문제

9.A student observes that radio signals can be received clearly in a valley surrounded by hills, but television signals cannot. Which property of waves explains this?
Medium
- ADiffraction
- BRefraction
- CReflection
- DAbsorption
10.Which of the following is a benefit of digital signalling over analogue signalling?
Easy
- AThe signal can be regenerated with minimal noise
- BDigital signals have a shorter range
- CDigital signals cannot be checked for errors
- DDigital signals have a lower data transmission rate
11.A radiographer stands behind a lead screen during X-ray procedures. Why is lead used?
Easy
- ALead absorbs a lot of X-ray radiation
- BLead reflects X-rays away from the radiographer
- CLead emits X-rays that cancel out harmful radiation
- DLead is a good conductor of electricity
12.Which type of electromagnetic radiation is used for sterilising medical equipment?
Easy
- AGamma rays
- BX-rays
- CUltraviolet
- DInfrared
13.A student is using a mobile phone to make a call. Which type of electromagnetic radiation is used to transmit the signal between the phone and the nearest mast?
Easy
- ARadio waves
- BMicrowaves
- CInfrared
- DVisible light
14.A geostationary satellite orbits at a height of 36 000 km above the Earth's surface. A signal is sent from Earth to the satellite and back. Given that all electromagnetic waves travel at 3.0 × 10⁸ m/s in a vacuum, what is the approximate time delay for the signal to make this round trip?
Medium
- A0.12 s
- B0.24 s
- C0.48 s
- D0.72 s
15.An X-ray machine uses a beam of X-rays to produce an image of a patient's bones. Which property of X-rays makes them suitable for this purpose?
Easy
- AThey have a long wavelength.
- BThey are absorbed by bone more than by soft tissue.
- CThey are reflected by bone.
- DThey travel at a lower speed in bone.
16.A technician uses an optical fibre of refractive index 1.3. What is the critical angle for the glass? (sin c = 1/n)
Medium
- A35.3°
- B40.5°
- C50.3°
- D55.6°
17.A student looks at an oscilloscope trace that shows a signal that varies continuously between a maximum and minimum value. What type of signal is this?
Easy
- ADigital signal
- BAnalogue signal
- CBinary signal
- DPulse signal
18.A polar satellite orbits at 200 km above sea level. A geostationary satellite orbits at 36 000 km. Which statement about the time delay for signals is correct?
Easy
- AThe polar satellite has a longer time delay because it is closer.
- BThe geostationary satellite has a longer time delay because it is farther.
- CBoth have the same time delay because they use the same type of wave.
- DThe time delay depends only on the frequency of the wave.
19.Which of the following lists the electromagnetic spectrum in order of increasing frequency?
Easy
- ARadio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays
- BGamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, radio waves
- CRadio waves, infrared, microwaves, visible light, ultraviolet, X-rays, gamma rays
- DVisible light, infrared, radio waves, microwaves, ultraviolet, X-rays, gamma rays
20.Which type of electromagnetic radiation has the highest frequency?
Easy
- ARadio waves
- BInfrared
- CUltraviolet
- DGamma rays
21.A technician uses an optical fibre made of glass with refractive index 1.5. What is the critical angle of the glass? (Use sin c = 1/n)
Medium
- A41.8°
- B48.6°
- C33.7°
- D56.4°
22.Which of the following is a correct use of ultraviolet radiation?
Easy
- Asterilising water
- Bheating food in a microwave oven
- Ctransmitting television signals from a satellite
- Dimaging bones in a hospital
23.A geostationary satellite orbits at a height of 36 000 km above the Earth's surface. A signal is sent from Earth to the satellite and back. Given that all electromagnetic waves travel at 3.0 × 10⁸ m/s in a vacuum, what is the approximate time delay for the signal to travel from Earth to the satellite?
Medium
- A0.12 s
- B0.24 s
- C0.48 s
- D1.2 s
24.Which type of electromagnetic radiation has the lowest frequency?
Easy
- Aradio waves
- Bmicrowaves
- Cinfrared
- Dvisible light
25.Which of the following statements about electromagnetic waves is correct?
Easy
- AAll electromagnetic waves travel at the same speed in a vacuum.
- BElectromagnetic waves are longitudinal waves.
- CElectromagnetic waves require a medium to travel through.
- DThe speed of electromagnetic waves in air is less than in a vacuum.
26.All electromagnetic waves travel at the same speed in a vacuum.
Easy
True or false?
27.Excessive exposure to which type of electromagnetic radiation is most likely to cause skin cancer?
Easy
- AUltraviolet
- BInfrared
- CMicrowaves
- DRadio waves
28.Gamma rays have a longer wavelength than radio waves.
Easy
True or false?
29.Which of the following statements about digital and analogue signals is correct?
Easy
- ADigital signals can take any value, while analogue signals have only two discrete values.
- BAnalogue signals vary continuously, while digital signals take only two discrete values.
- CDigital signals are used only for sound transmission, while analogue signals are used for video.
- DAnalogue signals have a higher rate of data transmission than digital signals.
30.Which of the following are uses of gamma rays? (Select all that apply.)
Easy
- ASterilising food
- BSterilising medical equipment
- CTreatment of cancer
- DSecurity marking
31.Complete the sentence.
Easy
The electromagnetic spectrum is arranged in order of decreasing ____ and increasing ____.
32.What is the speed of all electromagnetic waves in a vacuum? Give your answer in m/s.
Easy
33.State one benefit of digital signalling over analogue signalling.
Easy
34.A geostationary satellite orbits at a height of 36 000 km above the Earth's surface. Calculate the time taken for a microwave signal to travel from Earth to the satellite. (Speed of electromagnetic waves in vacuum = 3.0 × 10⁸ m/s.)
Medium
35.Match each type of electromagnetic wave to its primary use.
Easy
- Radio waves
- Microwaves
- Infrared
- Radio and television transmissions
- Satellite television
- Thermal imaging
36.Arrange the following regions of the electromagnetic spectrum in order of increasing frequency (lowest frequency first).
Easy
- Visible light
- X-rays
- Microwaves
- Gamma rays
37.Arrange the following types of electromagnetic radiation in order of increasing frequency (lowest frequency first).
Easy
- Ultraviolet
- Microwaves
- Gamma rays
- Visible light
38.A student uses a microwave oven to heat food. Which statement explains why microwaves can heat the food?
Medium
- AMicrowaves are absorbed by water molecules in the food, causing them to vibrate and produce heat.
- BMicrowaves are reflected by the metal walls of the oven, concentrating the energy on the food.
- CMicrowaves ionise the atoms in the food, releasing heat energy.
- DMicrowaves have a very high frequency, which directly heats the food.
39.Complete the sentence about the electromagnetic spectrum.
Easy
As the frequency of electromagnetic waves increases, their wavelength ____. (Fill in the blank with 'increases' or 'decreases')
40.Analyse teacher-provided frequency and wavelength values for electromagnetic waves in a vacuum. What is the independent variable?
Easy
- Athe corresponding wavelength
- Bthe number of repeated trials
- Cthe frequency of the radiation
- Dthe scientific explanation written afterwards
41.Analyse teacher-provided frequency and wavelength values for electromagnetic waves in a vacuum. Which observation or quantity is the dependent variable?
Easy
- Athe frequency of the radiation
- Bthe title given to the investigation
- Cthe number of references in the report
- Dthe corresponding wavelength
42.Analyse teacher-provided frequency and wavelength values for electromagnetic waves in a vacuum. Which decision best controls another factor in this comparison?
Medium
- Acompare propagation in a vacuum
- Bchange every condition for each trial
- Cuse a different measurement method for every result
- Drecord only results that agree with the prediction
43.Analyse teacher-provided frequency and wavelength values for electromagnetic waves in a vacuum. Why should the class repeat measurements or check multiple comparable observations?
Medium
- ATo guarantee that every systematic error disappears
- BTo assess variation and judge how consistent the evidence is
- CTo make an unsupported prediction become correct
- DTo avoid reporting results that disagree with a model
44.A class is evaluating an application of the electromagnetic spectrum and risk. Which statement identifies a relevant limitation?
Hard
- AAll scientific models reproduce every feature of the real world
- BOne favourable result proves that a technology has no disadvantages
- CRisk depends on type, dose and exposure; non-ionising radiation can still cause harm through heating or other interactions.
- DA conclusion needs no evidence when a scientific term is used
45.Analyse teacher-provided frequency and wavelength values for electromagnetic waves in a vacuum. Which conclusion is most justified by a controlled comparison?
Hard
- AA claim that the result must hold in all possible conditions
- BA claim that alternative explanations never need testing
- CA claim based only on the most convenient observation
- DA conclusion restricted to the tested conditions, with uncertainty and limitations stated
46.Analyse teacher-provided frequency and wavelength values for electromagnetic waves in a vacuum. Select the two practices that strengthen the validity of this comparison.
Medium
- Acompare propagation in a vacuum
- Bchange the measurement method whenever a result is unexpected
- Crecord the corresponding wavelength using the same agreed procedure
- Dreport only observations that confirm the prediction
47.When evaluating evidence about the electromagnetic spectrum and risk, select the two scientifically defensible statements.
Hard
- AOne result proves the explanation in every situation
- BRisk depends on type, dose and exposure; non-ionising radiation can still cause harm through heating or other interactions.
- CA conclusion should state the conditions and uncertainty of the evidence
- DModels never need revision when new evidence appears
48.Design a fair investigation for this question: Analyse teacher-provided frequency and wavelength values for electromagnetic waves in a vacuum. Identify what to compare, what to record and one control.
Medium
49.Explain one use of the science in the electromagnetic spectrum and risk and evaluate one limitation of the evidence or application.
Hard
50.An electromagnetic wave in a vacuum has frequency 6.0 x 10¹⁴ Hz. Use wave speed 3.0 x 10⁸ m/s. What is its wavelength?
Hard
- A5.0 x 10^-7 m
- B2.0 x 10⁶ m
- C1.8 x 10²³ m
- D5.0 x 10^-6 m
51.A student claims non-ionising radiation is always harmless. Which response evaluates the claim correctly?
Hard
- AAll non-ionising radiation removes electrons from atoms
- BNon-ionising radiation can still cause harm; effects depend on type, intensity and exposure
- CEvery exposure has exactly the same risk
- DOnly radiation with a visible colour can cause harm

복습 노트

## Big idea: the electromagnetic spectrum and risk - **Key concept: Relationships.** All electromagnetic waves travel at the same speed in a vacuum. Higher frequency means shorter wavelength and greater photon energy. - **Related concepts: Models and evidence.** Use a scientific explanation to make predictions, then test it against observations. - **Global context: Scientific and technical innovation.** Different spectrum regions support communication, imaging and treatment. ## Electromagnetic Waves - The **electromagnetic spectrum** is a continuous range of waves arranged by **wavelength** or **frequency**. - Longer wavelength → lower frequency; shorter wavelength → higher frequency. - Order from longest to shortest wavelength: **radio waves**, **microwaves**, **infrared**, **visible light** (ROYGBIV), **ultraviolet**, **X-rays**, **gamma rays**. - All EM waves are **transverse** waves that transfer energy. - All EM waves travel at the same speed in a vacuum: **3.0 × 10⁸ m/s** (also approximately the speed in air). - Visible light is only a small part of the EM spectrum. ## Uses of Electromagnetic Waves - **Radio waves**: radio/TV transmissions, astronomy, RFID. - **Microwaves**: satellite TV, mobile phones, microwave ovens, WiFi. - **Infrared**: remote controls, thermal imaging, optical fibres, intruder alarms. - **Visible light**: vision, photography, illumination. - **Ultraviolet**: security marking, detecting fake bank notes, sterilising water, fluorescence. - **X-rays**: medical scanning, security scanners (absorbed by bone, pass through tissue). - **Gamma rays**: sterilising food/equipment, cancer detection and treatment. ## Dangers of Electromagnetic Waves - Higher frequency EM waves carry more energy and can **ionise** atoms (UV, X-rays, gamma rays). - **Microwaves**: internal heating of body cells (water absorption). - **Infrared**: skin burns. - **Ultraviolet**: skin cancer, eye damage; protection via sunscreen and sunglasses. - **X-rays and gamma rays**: cell mutation, DNA damage, cancer; radiographers use lead screens. - Radiation risk depends on radiation type, absorbed dose, exposure and the tissue affected. Greater electromagnetic frequency increases photon energy but does not by itself determine risk. ## Communications - **Microwaves** are used for satellite communication (mobile phones, satellite TV) because they are not absorbed/reflected by the atmosphere. - **Radio waves** diffract around hills (similar wavelength to obstacles), used for local radio and Bluetooth. - **Optical fibres** use visible light or infrared for high-speed broadband; high frequency allows high data rates. - **Geostationary satellites**: orbit at 36 000 km, period 24 h, used for broadcasting; longer time delay. - **Low‑orbit/polar satellites**: orbit at ~200 km, shorter delay, used for weather and imaging. ## Digital & Analogue Signals - **Analogue signals** vary continuously and can take any value. - **Digital signals** have only two states (0/1, high/low). - Digital signals can be **regenerated** with minimal noise, giving larger range and higher data rate. - Extra data can be added to digital signals for error checking. - Digital sampling converts an analogue signal to digital by recording at set time intervals. ## Think like a scientist - Analyse teacher-provided frequency and wavelength values for electromagnetic waves in a vacuum. - **Comparison:** the frequency of the radiation. **Outcome:** the corresponding wavelength. - **Control:** compare propagation in a vacuum. Explain why this makes the comparison fairer. - **Evidence:** Use a consistent method, repeated observations where appropriate and a table with labelled quantities and units. Keep unexpected results and investigate their cause. - **Safety:** Practical activities need teacher supervision and an appropriate risk assessment. Use the provided data or simulation where the investigation specifies it. - **Inquiry task:** State a testable question, predict the outcome using the science, then explain how your observations would support or challenge the prediction. ## Evaluate the science - Different spectrum regions support communication, imaging and treatment. - Risk depends on type, dose and exposure; non-ionising radiation can still cause harm through heating or other interactions. - **Evaluation task:** Link your conclusion to evidence, identify a limitation and suggest a specific improvement. Distinguish a measured result from an explanation of its cause.

Analogue & Digital Signals: Distinguish between analogue and digital signals and state advantages of digital signalling.
EM Spectrum Order: Recall the order of the electromagnetic spectrum by wavelength and frequency, from radio waves to gamma rays.
EM Wave Dangers: Explain the harmful effects of excessive exposure to electromagnetic waves, particularly ionising radiation.
Satellite Communications: Compare geostationary and low-orbit satellites and explain their use in communications with microwaves.
EM Wave Uses: Describe typical uses of each region of the electromagnetic spectrum, including communication, medicine, and security.
EM Wave Properties: State that all electromagnetic waves are transverse, travel at the same speed in a vacuum, and transfer energy.
Designing scientific inquiries: Plan a fair comparison: Analyse teacher-provided frequency and wavelength values for electromagnetic waves in a vacuum.
Evaluating evidence and impacts: Different spectrum regions support communication, imaging and treatment. Risk depends on type, dose and exposure; non-ionising radiation can still cause harm through heating or other interactions.
Electromagnetic Waves: The **electromagnetic spectrum** is a continuous range of waves arranged by **wavelength** or **frequency**.
Uses of Electromagnetic Waves: **Radio waves**: radio/TV transmissions, astronomy, RFID.
Dangers of Electromagnetic Waves: Higher frequency EM waves carry more energy and can **ionise** atoms (UV, X-rays, gamma rays).
Communications: **Microwaves** are used for satellite communication (mobile phones, satellite TV) because they are not absorbed/reflected by the atmosphere.
Digital & Analogue Signals: **Analogue signals** vary continuously and can take any value.
electromagnetic spectrum: The **electromagnetic spectrum** is a continuous range of waves arranged by **wavelength** or **frequency**.
wavelength: The **electromagnetic spectrum** is a continuous range of waves arranged by **wavelength** or **frequency**.
frequency: The **electromagnetic spectrum** is a continuous range of waves arranged by **wavelength** or **frequency**.

플래시카드

Which of the following lists the electromagnetic spectrum in order of decreasing wavelength?

Radio waves, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays The electromagnetic spectrum is arranged from longest to shortest wavelength: radio waves, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays. Option A is correct.

All electromagnetic waves travel at the same speed in a vacuum. What is this speed?

3.0 × 10⁸ m/s The speed of all electromagnetic waves in a vacuum is 3.0 × 10⁸ m/s. Option A is correct.

Which type of electromagnetic radiation is used for television remote controls?

Infrared Television remote controllers use infrared radiation. Option A is correct.

Which of the following is a harmful effect of excessive exposure to ultraviolet radiation?

Skin cancer Ultraviolet radiation can cause skin cancer and eye conditions. Internal heating is from microwaves, skin burns from infrared, and DNA mutation from X-rays/gamma rays. Option A is correct.

Which type of electromagnetic radiation has a wavelength of about 1 km?

Radio waves Radio waves have wavelengths of around a kilometre. Option A is correct.

A geostationary satellite orbits at a height of 36 000 km above the Earth's surface. What is its orbital period?

24 hours Geostationary satellites have an orbital period of 24 hours. Option A is correct.

Which property increases as you move from radio waves to gamma rays in the electromagnetic spectrum?

Frequency As wavelength decreases from radio to gamma, frequency increases. Speed in a vacuum is constant. Option A is correct.

Which type of signal can only take one of two discrete values?

Digital signal A digital signal can only take two values (e.g., 0 or 1). An analogue signal varies continuously. Option A is correct.

A student observes that radio signals can be received clearly in a valley surrounded by hills, but television signals cannot. Which property of waves explains this?

Diffraction Radio waves have longer wavelengths (about 1 km) similar to the size of hills, so they diffract around obstacles. TV signals have shorter wavelengths and diffract less. Option A is correct.

Which of the following is a benefit of digital signalling over analogue signalling?

The signal can be regenerated with minimal noise Digital signals can be regenerated accurately, reducing noise and increasing range. They also allow error checking and higher data rates. Option A is correct.

A radiographer stands behind a lead screen during X-ray procedures. Why is lead used?

Lead absorbs a lot of X-ray radiation Lead absorbs a lot of radiation, protecting the radiographer from exposure. Option A is correct.

Which type of electromagnetic radiation is used for sterilising medical equipment?

Gamma rays Gamma rays are used to sterilise food and medical equipment by killing bacteria. Option A is correct.

A student is using a mobile phone to make a call. Which type of electromagnetic radiation is used to transmit the signal between the phone and the nearest mast?

Microwaves Mobile phones use microwaves for communication.

A geostationary satellite orbits at a height of 36 000 km above the Earth's surface. A signal is sent from Earth to the satellite and back. Given that all electromagnetic waves travel at 3.0 × 10⁸ m/s in a vacuum, what is the approximate time delay for the signal to make this round trip?

0.24 s Distance = 2 × 36 000 km = 72 000 km = 7.2 × 10⁷ m. Time = distance / speed = (7.2 × 10⁷) / (3.0 × 10⁸) = 0.24 s.

An X-ray machine uses a beam of X-rays to produce an image of a patient's bones. Which property of X-rays makes them suitable for this purpose?

They are absorbed by bone more than by soft tissue. X-rays are absorbed by denser materials like bone, leaving a shadow on the photographic film. Soft tissue absorbs less, so the bone appears clearly.

A technician uses an optical fibre of refractive index 1.3. What is the critical angle for the glass? (sin c = 1/n)

50.3° Critical angle c = sin⁻¹(1/n) = sin⁻¹(1/1.3) ≈ sin⁻¹(0.769) ≈ 50.3°.

How would you design the inquiry for the electromagnetic spectrum and risk?

Analyse teacher-provided frequency and wavelength values for electromagnetic waves in a vacuum. Compare the frequency of the radiation; record the corresponding wavelength; compare propagation in a vacuum.

What limitation matters when applying the electromagnetic spectrum and risk?

Risk depends on type, dose and exposure; non-ionising radiation can still cause harm through heating or other interactions.

Unlock all 51 questions, flashcards & more

무료 계정을 만들어 이 주제의 모든 문제, 슬라이드, 플래시카드, 복습 노트를 확인하세요.

가입 — 무료 로그인

기출 문제

이 주제의 기출 문제 연습이 곧 나와요.

곧 출시