Topic 5.19-5.24 — Dangers and uses of Electromagnetic waves

Question 1

What is the relationship associated with the potential danger of an electromagnetic wave?

Answer 1

The potential danger associated with an electromagnetic wave increases with increasing frequency

Question 1

What is the harmful effect on people of excessive exposure to microwaves?

Answer 1

The internal heating of body cells

Question 1

What is the harmful effect on people of excessive exposure to infrared radiation?

Answer 1

Skin burns

Question 1

What is the harmful effect on people of excessive exposure to ultraviolet radiation?

Answer 1

Damage to surface cells and eyes, leading to skin cancer and eye conditions

Question 1

What is the harmful effect on people of excessive exposure to x-rays and gamma rays?

Answer 1

Mutation or damage to cells in the body

Question 1

Describe some uses of radio waves

Answer 1

Broadcasting, communications and satellite transmissions as they are transmitted easily through air, do not cause damage if absorbed by the human body and can be reflected to change their direction.

Question 2

Describe some uses of microwaves

Answer 2

Cooking, communications and satellite transmissions.

Cooking - They have frequencies which are easily absorbed by molecules in food and the internal energy of the molecules increase when they absorb microwaves.

Communications, satellite transmissions - Microwaves also pass easily through the atmosphere, so they can pass between stations on Earth and satellites in orbit.

Question 3

Describe some uses of infrared radiation

Answer 3

Cooking, thermal imaging, short range communications, optical fibres, television remote controls and security systems.

Cooking - It has frequencies which are absorbed by some chemical bonds and the internal energy of the bonds increases when they absorb infrared light, which causes heating.

Thermal imaging - The human eye cannot see this light. All objects emit infrared light. Infrared cameras can detect it.

Question 4

Describe some uses of visible light

Answer 4

Vision, photography and illumination. It is the light that we can see.

Question 5

Describe some uses of ultraviolet radiation

Answer 5

Security marking, fluorescent lamps, detecting forged bank notes and disinfecting water.

Fluorescent lamps, detecting forged bank notes - Fluorescent substances absorb ultraviolet light produced and re-emit the energy as visible light.

Disinfecting water - The hazardous properties of UV mean it will kill bacteria.

Question 5

Describe some uses of x-rays

Answer 5

Observing the internal structure of objects, airport security scanners and medical x-rays.

Medical x-rays - They are transmitted through body tissues with very little absorption but are absorbed by dense structures like bones allowing them to identify broken bones.

Question 6

Describe some uses of gamma rays

Answer 6

Sterilising food and medical equipment, and the detection of cancer and its treatment.

Gamma rays are produced by changes in the nucleus of an atom and form in nuclear radiation. They are transmitted through body tissues with very little absorption.

Question 7

Describe radio waves connection to electrical circuits

Answer 7

Radio waves can be produced by, or can themselves induce, oscillations in electrical circuits

Question 8

What can changes in atoms and nuclei do?

Answer 8

Changes in atoms and nuclei can generate radiations over a wide frequency range and be caused by the absorption of a range of radiations