This is a powerpoint about electromagnetic spectrum for grade 7 science

1. Activity: “Door of
Knowledge”

3. Electromagnetic waves with the
shortest wavelengths and highest
frequencies is Gamma ray.

4. Electromagnetic waves with the
shortest wavelengths and highest
frequencies is Gamma ray.

5. What term describes the entire
range of electromagnetic
frequencies, from radio waves to
gamma rays?
a. Sound wave
b. Electromagnetic Spectrum
c. Light
d. Waves

6. What term describes the entire
range of electromagnetic
frequencies, from radio waves to
gamma rays?
a. Sound wave
b. Electromagnetic Spectrum
c. Light
d. Waves

7. Based on the electromagnetic
spectrum, which of the following has
the lower energy and frequency?
a. X-rays
a. Gamma rays
b. Radio waves
c. Infrared waves

8. Based on the electromagnetic
spectrum, which of the following has
the lower energy and frequency?
a. X-rays
a. Gamma rays
b. Radio waves
c. Infrared waves

9. A rainbow is formed when sunlight hits
raindrops in the air. The light bends, or
refracts, as it enters the droplet, then reflects
off the inside surface of the droplet, and
finally exits the droplet. This bending and
reflecting of light make the colors spread out,
creating the beautiful arc of colors we see in
the sky.

11. What represents this?

12. Short wavelength – High Energy

13. Free item!!
(Your seatmate will be next to pick a
door)

14. Activity: What color am I?

15. Activity: What color am I?

16. Activity: What color am I?

17. Characteristics of a Wave
1. Frequency (Symbol: f Unit: Hertz,
Hz) - number of complete waves
passing at a point every one
second.
2. Amplitude (Symbol: A Unit: meter,
m) - the maximum distance of a
wave from its rest position.

18. Characteristics of a Wave
3. Wavelength (Symbol: λ Unit:
meter, m) - distance between two
successive crests or troughs

19. Characteristics of a Wave

20. Characteristics of a Wave

21. High frequency
High amplitude
Low frequency
High amplitude

22. Characteristics of a Wave
4. Speed of Light (Unit: meter per
second, m/s)
• distance travelled by light per unit
time
• all forms of electromagnetic radiation
moves at exactly the same speed in
vacuum

23. Characteristics of a Wave
• speed of light = 3.0 x 108 m/s (in
vacuum)
Formula:
speed of light = wavelength x frequency symbol
c = λ f

24. Characteristics of Light
1. Color
• Visible light has wavelengths of 400
nanometer (nm) and 750 nanometer
(nm).
• These wavelengths are represented
by colors.

26. Characteristics of Light
Note: The wavelength of light is
inversely proportional to its frequency
• As the wavelength of light
decreases, the frequency increases.
• As the wavelength of light increases,
the frequency decreases.

27. 2. Intensity or Brightness
The height of the amplitude tells the
brightness of light. Thus, the higher
amplitude corresponds to a brighter
light while lower amplitude corresponds
to a dull light.

28. WELCOME TO CLASS!

29. LEARNING OBJECTIVES
Explain the characteristics of light
At the end of the lesson, the students should be able to:
Compare the color and intensity of light through
Venn diagram
Relate the characteristics of light in real life
experiences