1. Electromagnetic waves travel in a vacuum with a speed of:
Answer:
Explanation:
Electromagnetic waves travel at the speed of light, which is approximately 3 x 10^8 m/s in a vacuum.
2. Which of the following is NOT an electromagnetic wave?
Answer:
Explanation:
Sound waves are mechanical waves, while the rest are types of electromagnetic waves.
3. The oscillations in electromagnetic waves are:
Answer:
Explanation:
Electromagnetic waves consist of oscillating electric and magnetic fields perpendicular to each other.
4. Which electromagnetic wave has the longest wavelength?
Answer:
Explanation:
Radio waves have the longest wavelength among the given options.
5. In the electromagnetic spectrum, the waves used for satellite communication are:
Answer:
Explanation:
Microwaves, especially those in the GHz range, are commonly used for satellite communication.
6. Which of the following electromagnetic waves is used for treating muscle pain?
Answer:
Explanation:
Infrared lamps are used in physiotherapy to treat muscle pains and other ailments.
7. Which part of the electromagnetic spectrum is absorbed by the ozone layer?
Answer:
Explanation:
The ozone layer absorbs the harmful ultraviolet rays from the Sun.
8. Which electromagnetic wave can ionize atoms?
Answer:
Explanation:
Gamma rays have high energy and can ionize atoms.
9. The phenomenon by which electromagnetic waves change their direction at the boundary of a medium is called:
Answer:
Explanation:
Refraction is the bending of waves when they enter a different medium.
10. Which of the following is used for detecting flaws in metal structures?
Answer:
Explanation:
X-rays are used in radiography to detect cracks and flaws in metal structures.
11. Which of the following has the shortest wavelength?
Answer:
Explanation:
In the visible spectrum, blue light has a shorter wavelength than the other colors mentioned.
12. Electromagnetic waves can travel through:
Answer:
Explanation:
Electromagnetic waves can propagate through a vacuum as well as through many solid materials.
13. Which of the following electromagnetic waves can cause sunburn?
Answer:
Explanation:
Overexposure to ultraviolet rays from the Sun can cause sunburn.
14. The speed of electromagnetic waves in a medium depends on:
Answer:
Explanation:
The speed of electromagnetic waves in a medium is determined by the properties of the medium and not the wave's frequency or amplitude.
15. The range of frequencies for visible light is:
Answer:
Explanation:
The frequencies for visible light lie in the terahertz (THz) range, approximately between 400 and 700 THz.