Question

select the true statements about electromagnetic waves. choose 2 answers: a electromagnetic waves dont need a matter medium to travel through. b some electromagnetic waves travel faster than others in a vacuum. c human eyes can see all electromagnetic waves directly. d different parts of the electromagnetic spectrum have different frequencies and wavelengths.

Explanation:

• For option A: Electromagnetic waves are transverse waves that can propagate through a vacuum (no matter medium), unlike mechanical waves. So this statement is true.
• For option B: In a vacuum, all electromagnetic waves travel at the speed of light ($c = 3\times10^{8}\ m/s$), so they have the same speed. Thus, this statement is false.
• For option C: Human eyes can only detect a small portion of the electromagnetic spectrum (visible light), not all. So this statement is false.
• For option D: The electromagnetic spectrum consists of waves with different frequencies and wavelengths (e.g., radio waves have low frequency and long wavelength, gamma rays have high frequency and short wavelength). This statement is true.

Answer:

A. Electromagnetic waves don't need a matter medium to travel through.
D. Different parts of the electromagnetic spectrum have different frequencies and wavelengths.