Louis de Broglie introduced the idea that particles like electrons exhibit wave-like properties, with a wavelength inversely proportional to momentum. This de Broglie wavelength formula is λ = h/p = h/mv, where h is Planck's constant, p is momentum, m is mass, and v is velocity. The document provides examples calculating de Broglie wavelength for different particles like muons and electrons moving at given speeds. Students are expected to understand de Broglie's hypothesis of matter waves and be able to calculate de Broglie wavelength from momentum or velocity.

1. De Broglie
wavelength
Prepared by:
Daniel B. Anore

2. SORT THEM OUT
Rearrange the letter and form a word

3. MMTUMEO
MOMENTUM

4. WVAELEGTHN
WAVELENGTH

5. ASSM
MASS

6. VLCTYEOI
VELOCITY

7. OBJECTIVE
At the end of 60 minutes lesson, 85% of the
students CAN:
 recognize that all particles have an associated
wavelength called the de Broglie wavelength;
 describe de Broglie’s hypothesis of matter waves;
and
 calculate de Broglie wavelength of massive
particles that have a given momentum or velocity.

8. PRESENT YOUR IDEA
Make a concept about the topic below and
present it in class.
GROUP 1: Who is Louis de Broglie
GROUP 2: Explain de Broglie wavelength

9. Louis de Broglie
 Famous physicist, mostly known for his
contributions to the field of quantum mechanics.
 He revolutionized that field by introducing the idea
of the wave nature of electrons and particle-
wave duality.
 This theory started the branch of wave mechanics
and Louis de Broglie received the Nobel Prize in
Physics for this work in 1929

10. De Broglie wavelength
 Indicates that the wave associated with any moving particle has
a specific wavelength that depends on the particle’s momentum
 The formula for de Broglie wavelength is:
ʎ =
ℎ
𝑚𝑣
where,
 λ is wavelength
 h is Planck’s constant
 m is the mass of a particle
 v is the velocity

11. LIGHT
WAVE PARTICLE
Refraction &
Diffraction
Photoelectric
effect

12. De Broglie wavelength
 In 20th century, physicist Louis de Broglie
suggested that particle with mass such as
electron and protons could behave as a
wave.

13. E = 𝑚𝑐2
Where,
E = energy,
m = mass,
c = speed of light
EINSTEIN Planck’s theory
E = ℎ𝑓
Where,
E = energy,
h = Planck's constant
(6.626 x 10^-34 J*s)
f = frequency
𝑚𝑐2
= ℎ𝑓
v = 𝑓λ
𝑚𝑣2 = ℎ𝑓
𝑓 =
𝑣
λ
𝑚𝑣2
=
ℎ𝑣
λ
(
λ
𝑚𝑣2
)𝑚𝑣2
=
ℎ𝑣
λ
(
λ
𝑚𝑣2
)
𝝀 =
𝒉
𝒎𝒗
𝑚𝑣2 = ℎ𝑓
𝑃 = 𝑚𝑣
𝝀 =
𝒉
𝒑

14. De Broglie formula
ʎ =
𝒉
𝒑
=
𝒉
𝒎𝒗

15. Calculating the de Broglie
Wavelength of a Particle
 A muon has a rest mass of 1.89×10-28 kg. If
the muon is moving at a speed of 20 m/s,
what is its de Broglie wavelength?

16. ʎ =
ℎ
𝑝
=
ℎ
𝑚𝑣
ʎ =
ℎ
𝑚𝑣
ʎ =
6.626𝑥10−34
𝐽 · 𝑠
(1.89×10−28 kg)(20 m/s)
ʎ =
6.626𝑥10−34𝑘𝑔
𝑚2
𝑠2 · 𝑠
(1.89×10−28 kg)(20 m/s)
ʎ =
6.626𝑥10−34𝑚
3.78×10−27
ʎ = 1.75×10−7m

17. Calculating the de Broglie
Wavelength of a Particle
 Find the de Broglie wavelength for an electron
moving at the speed of 5.0×10⁶ m/s (mass of
an electron is 9.11×10−31kg )

18. ʎ =
ℎ
𝑝
=
ℎ
𝑚𝑣
ʎ =
ℎ
𝑚𝑣
ʎ =
6.626𝑥10−34
𝐽 · 𝑠
(9.11×10−31kg)(5×10⁶m/s)
ʎ =
6.626𝑥10−34𝑘𝑔
𝑚2
𝑠2 · 𝑠
(9.11×10−31kg)(5×10⁶m/s)
ʎ =
6.626𝑥10−34𝑚
4.56×10−24
ʎ = 1.5×10−10m

19. What is de Broglie
wavelength?
De Broglie wavelength indicates that the wave associated
with any moving particle has a specific wavelength that
depends on the particle’s momentum.

20. What is the formula for de
Broglie wavelength?
ʎ =
𝒉
𝒑
=
𝒉
𝒎𝒗

21. DE BROGLIE
WAVELENGTH

22. THANK YOU FOR
LISTENING!!