OCR GCSE Physics A (Gateway)
OCR GCSE Physics A P5.2 The Electromagnetic Spectrum Exam Questions
Free OCR GCSE Physics A exam questions for P5.2 The Electromagnetic Spectrum, with a mark scheme for every pack. Covers electromagnetic waves, the order of the spectrum, uses, dangers, ionising radiation, emission and absorption of radiation.
P5.2 The Electromagnetic Spectrum exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About OCR GCSE Physics A P5.2 The Electromagnetic Spectrum
P5.2 in the P5 Waves in matter chapter of OCR Gateway Physics A covers the family of electromagnetic waves. You need to recall that all EM waves are transverse and travel at the same speed in a vacuum, the order of the spectrum, and how wavelength and frequency change across it. The topic covers uses of each region, and the hazards of ultraviolet, X-rays and gamma rays, which are ionising. You also learn that radio waves can be produced by oscillations in electrical circuits and how all bodies emit and absorb radiation depending on their temperature. Examiners like uses and dangers questions and wave equation calculations.
What you need to know
- Properties EM waves are transverse, travel at 3 x 10^8 m/s in a vacuum and transfer energy from source to absorber.
- Order Radio, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays: in this order frequency increases and wavelength decreases.
- Uses Radio: broadcasting and communication. Microwaves: satellite communication and cooking. Infrared: heaters, cooking, cameras, remote controls. Visible: fibre optics. UV: energy-efficient lamps and sun tanning. X-rays and gamma: medical imaging and treatment.
- Hazards Ultraviolet can age skin prematurely and increase the risk of skin cancer. X-rays and gamma rays are ionising and can cause mutation of genes and cancer.
- Production and absorption Radio waves can be produced by oscillations in electrical circuits and can induce an alternating current in a receiver. Changes in atoms and nuclei can produce EM waves; gamma rays come from the nucleus.
- Temperature and radiation All bodies emit radiation; the intensity and wavelength distribution depend on temperature. Hotter bodies emit more radiation at shorter wavelengths. A body at constant temperature absorbs and emits at the same rate.
Common mistakes in P5.2 The Electromagnetic Spectrum
- Saying some EM waves are longitudinal. All EM waves are transverse.
- Saying radio waves or microwaves are ionising. Only UV, X-rays and gamma rays are ionising.
- Thinking higher frequency waves travel faster. All EM waves have the same speed in a vacuum.
- Saying an object at constant temperature has stopped emitting radiation. It emits and absorbs at equal rates.
- Getting the order backwards when asked about increasing wavelength. Radio has the longest wavelength.
Try three P5.2 The Electromagnetic Spectrum exam-style questions
1. A microwave oven uses waves of frequency 2.4 x 10^9 Hz. The speed of EM waves is 3.0 x 10^8 m/s. Calculate the wavelength. (3 marks)
Show the mark scheme answer
Wavelength = speed / frequency; = 3.0 x 10^8 / 2.4 x 10^9; = 0.125 m (0.13 m).
2. Give one use and one hazard of X-rays. (2 marks)
Show the mark scheme answer
Use: imaging bones or medical imaging (or treating cancer); hazard: ionising, can cause gene mutation or cancer.
3. Explain why the Earth's temperature stays roughly constant. (3 marks)
Show the mark scheme answer
The Earth absorbs radiation from the Sun; it also emits radiation into space; when the rates of absorption and emission are equal the temperature is constant.
P5.2 The Electromagnetic Spectrum FAQs
What does OCR GCSE Physics A (Gateway Science) P5.2 The Electromagnetic Spectrum cover?
It covers the properties and order of EM waves, their uses and hazards, how they are produced and absorbed, and how temperature affects emitted radiation.
Which paper is P5.2 examined on?
Topics P5 to P8 are assessed on Paper 2 (Foundation) or Paper 4 (Higher), which can also draw on knowledge from P1 to P4 and practical skills.
How should I revise the electromagnetic spectrum?
Learn the order with a mnemonic, then make a table with one use and one hazard for each region, noting which regions are ionising.
