Electromagnetic | MCQs

Explanation

Security scanners used at night typically employ infrared (IR) technology to detect heat signatures, allowing for nighttime surveillance.

IR waves have a longer wavelength than visible light, making them ideal for detecting heat radiation from objects or people.

Explanation

Electromagnetic waves are typically listed in order of increasing wavelength (or decreasing frequency) as follows:

• Gamma-rays (shortest wavelength, highest frequency)
• X-rays
• Microwaves (longer wavelength, lower frequency)

Explanation

The correct answer is: Light waves, Radio waves, Microwaves

This group consists only of electromagnetic waves, which are waves that propagate through the electromagnetic field.

They do not require a physical medium to propagate.

Explanation

X-rays are a type of electromagnetic radiation that are commonly used in radiotherapy to destroy cancer cells.

They have enough energy to penetrate deep into tissue and damage the DNA of cancer cells, slowing their growth or killing them.

Explanation

• The flash of light from lightning is a form of electromagnetic radiation, and as such, it travels at the speed of light.
• It is denoted by the letter c.

It is equal to:

• 3 x 10^8 meters per second (m/s) in scientific notation
• 300,000 kilometers per second (km/s) in metric units
• 186,282 miles per second (mi/s) in imperial units