Waves, Optics, and the Electromagnetic Spectrum Quiz

Grade 12 · Science · Quiz

Test your understanding of wave behavior, optics, light, and the electromagnetic spectrum.

Questions

1. Which electromagnetic wave has the highest energy?

   1. Radio waves
   2. Visible light
   3. X-rays
   4. Gamma rays
   Show answer

   Answer: Gamma rays

   In the EM spectrum, gamma rays have the highest frequency and therefore the highest energy (E = hf). They are produced by nuclear reactions.

2. The speed of light in water is the same as in vacuum.

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   Answer: False

   Light slows down in any medium denser than vacuum. In water (n ≈ 1.33), light travels at about 2.26 × 10⁸ m/s, about 75% of its vacuum speed.

3. The number of wave cycles per second is called the wave's ___.

   Show answer

   Answer: frequency

   Frequency (f) is measured in hertz (Hz = cycles per second). Higher frequency means shorter wavelength for a given wave speed.

4. When light travels from water into air, it bends:

   1. Away from the normal
   2. Toward the normal
   3. Parallel to the surface
   4. It does not bend
   Show answer

   Answer: Away from the normal

   When light moves from a denser medium (water, n=1.33) to a less dense medium (air, n=1.00), it speeds up and bends away from the normal line.

5. Constructive interference occurs when two waves cancel each other out.

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   Answer: False

   Constructive interference occurs when waves add together (crests align), increasing amplitude. Destructive interference is when waves cancel out (crest meets trough).

6. Which type of lens corrects nearsightedness (myopia)?

   1. Convex lens
   2. Plane mirror
   3. Concave lens
   4. Convex mirror
   Show answer

   Answer: Concave lens

   Concave (diverging) lenses spread light rays outward. For a nearsighted eye (eyeball too long), they reduce the convergence so the image falls on the retina correctly.

7. Light traveling through a glass fiber stays inside due to ___ internal reflection.

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   Answer: total

   Total internal reflection occurs when the angle of incidence exceeds the critical angle, keeping light trapped inside the fiber. This enables high-speed data transmission.

8. Sound waves are transverse waves.

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   Answer: False

   Sound waves are longitudinal (compression) waves — particles vibrate parallel to the direction of wave travel. Light and other EM waves are transverse waves.

9. Planck's equation E = hf relates photon energy to:

   1. Wavelength
   2. Amplitude
   3. Frequency
   4. Speed
   Show answer

   Answer: Frequency

   Planck's equation E = hf shows photon energy is directly proportional to frequency, not wavelength or amplitude. Higher frequency = higher energy photon.

10. The Doppler effect explains why a siren sounds higher in pitch as it:

    1. Moves away from you
    2. Stops moving
    3. Approaches you
    4. Moves perpendicular to you
    Show answer

    Answer: Approaches you

    As a source approaches, wave fronts bunch together, increasing frequency (higher pitch). As it moves away, wave fronts spread, decreasing frequency (lower pitch).

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