Light is defined as what?

Light is defined as what?

• A. A wave of alternating electric and magnetic fields
• B. A stream of photons
• C. A mechanical wave
• D. A disturbance in the air

Answer: (A)

Light is an electromagnetic wave: it consists of electric and magnetic fields that oscillate and propagate through space. The electric and magnetic fields are perpendicular to each other and to the direction the light travels, and a changing electric field sustains the changing magnetic field so the wave moves without needing a medium. This distinguishes light from a mechanical wave, which requires a material substance to carry vibrations, and from a simple disturbance in air like sound. Describing light as photons captures its particle aspect, but the common definition emphasized in this context is a wave of alternating electric and magnetic fields, which is why that option is the best choice.

Light is an electromagnetic wave: it consists of electric and magnetic fields that oscillate and propagate through space. The electric and magnetic fields are perpendicular to each other and to the direction the light travels, and a changing electric field sustains the changing magnetic field so the wave moves without needing a medium. This distinguishes light from a mechanical wave, which requires a material substance to carry vibrations, and from a simple disturbance in air like sound. Describing light as photons captures its particle aspect, but the common definition emphasized in this context is a wave of alternating electric and magnetic fields, which is why that option is the best choice.