Question

choose all answers that apply:
a some forms of em radiation travel faster than others in a vacuum.
b human eyes cannot see the entire em spectrum directly.
c em radiation consists of oscillating electric and gravitational fields.
d em radiation has both wave and particle properties.

Explanation:

• Option A: In a vacuum, all forms of electromagnetic (EM) radiation travel at the speed of light \(c = 3\times10^{8}\space m/s\). So, this statement is incorrect.
• Option B: The human eye can only detect a small portion of the EM spectrum (visible light, approximately \(400 - 700\space nm\)). There are many forms of EM radiation like radio waves, X - rays, gamma rays etc. that are not visible to the human eye. So, this statement is correct.
• Option C: EM radiation consists of oscillating electric and magnetic fields (not gravitational fields). The electric and magnetic fields are perpendicular to each other and also perpendicular to the direction of wave propagation. So, this statement is incorrect.
• Option D: EM radiation has a dual nature. It can exhibit wave - like properties (e.g., diffraction, interference) and particle - like properties (e.g., the photoelectric effect, where it behaves as photons). So, this statement is correct.

Answer:

B. Human eyes cannot see the entire EM spectrum directly; D. EM radiation has both wave and particle properties.