Waves and Electromagnetic Spectrum Quiz

Grade 7 · Science · Quiz

Test your knowledge of wave properties, types of waves, and the electromagnetic spectrum.

Questions

1. Which property of a wave is most directly related to the amount of energy it carries?

   1. Wavelength
   2. Frequency
   3. Amplitude
   4. Wave speed
   Show answer

   Answer: Amplitude

   Amplitude measures how much energy a wave carries. A larger amplitude wave (like a tsunami versus a ripple) carries far more energy.

2. Which of the following is NOT an electromagnetic wave?

   1. X-ray
   2. Microwave
   3. Sound wave
   4. Gamma ray
   Show answer

   Answer: Sound wave

   Sound is a mechanical wave — it needs a medium to travel and is caused by pressure variations, not oscillating electric/magnetic fields. All the others are electromagnetic waves.

3. Which color of visible light has the highest frequency?

   1. Red
   2. Green
   3. Yellow
   4. Violet
   Show answer

   Answer: Violet

   In visible light, violet has the shortest wavelength and therefore the highest frequency and energy. Red has the longest wavelength and lowest frequency.

4. Electromagnetic waves require a medium such as air or water to travel.

   Show answer

   Answer: False

   Unlike mechanical waves (sound, ocean waves), electromagnetic waves do not need a medium. They travel as oscillating electric and magnetic fields and can move through the vacuum of space.

5. A doctor uses this type of electromagnetic radiation to see inside a patient's body:

   1. Radio waves
   2. Infrared waves
   3. X-rays
   4. Microwaves
   Show answer

   Answer: X-rays

   X-rays have enough energy to pass through soft tissue but are absorbed by denser structures like bones, creating images used in medical diagnosis.

6. If a wave has a frequency of 10 Hz and a wavelength of 3 meters, what is its speed?

   1. 3 m/s
   2. 10 m/s
   3. 13 m/s
   4. 30 m/s
   Show answer

   Answer: 30 m/s

   Wave speed = frequency × wavelength = 10 Hz × 3 m = 30 m/s. This relationship is the universal wave equation: v = f × λ.

7. The distance between two consecutive crests of a wave is called the ______.

   Show answer

   Answer: wavelength

   Wavelength (λ) is the distance between two identical points on consecutive waves — crest to crest or trough to trough. It is inversely proportional to frequency.

8. Microwaves used in ovens heat food by causing which molecules to vibrate?

   1. Carbon dioxide
   2. Nitrogen
   3. Water
   4. Oxygen
   Show answer

   Answer: Water

   Microwave ovens emit radiation at a frequency that is absorbed specifically by water molecules, causing them to vibrate and generate heat throughout the food.

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