Sec 4 Combined Science (Physics) EM Spectrum topical questions

State the speed of all electromagnetic waves in a vacuum.

List the seven regions of the electromagnetic spectrum in order of increasing frequency.

State one typical use of microwaves and one typical use of X-rays.

Name the type of EM wave whose over-exposure causes sunburn, and state one other harmful effect of over-exposure to this radiation.

A microwave link operates at 1.5 × 10⁹ Hz. (a) Calculate the wavelength. (b) Name the region of the spectrum.

Explain why gamma rays are used to sterilise sealed medical equipment, and state why radio waves could not do this job.

Compare radio waves and gamma rays in terms of (a) wavelength, (b) frequency, (c) penetration, (d) hazard to humans.

Explain why satellite TV dishes must receive microwaves from satellites in space, and why this shows EM waves need no medium.

Explain why people get sunburnt at the beach, why sunscreen reduces the risk, and why the risk of skin cancer rises with repeated sunburn.

A radio station broadcasts at 100 MHz and a second station at 200 MHz. (a) Calculate both wavelengths. (b) State the relationship between frequency and wavelength shown by the answers.

Match each use to its band and justify the choice: (a) cooking food quickly; (b) detecting a fever with a camera; (c) checking a banknote for forgery; (d) imaging a tooth; (e) killing bacteria in sealed surgical packs.

A radiographer takes X-ray images all day. (a) Explain why X-rays are hazardous. (b) Describe three precautions that reduce her exposure. (c) Explain why the benefit of a single diagnostic image usually outweighs the risk.