Page 242 - Physics Form 5 KSSM_Neat

Electrons are said to have wave-particle duality because they exhibit the properties of both
particles and waves. Light also possesses both wave and particle properties. Therefore, light and
electrons are said to have wave-particle duality. This duality is also found in all kinds of radiation
in the electromagnetic wave spectrum as well as in subatomic particles like protons and neutrons.

KEMENTERIAN PENDIDIKAN MALAYSIA

Problem Solving for Photon Energy and Power

LET’S ANSWER
Example 1 LET’S ANSWER
A 50 W lamp emits red light with a wavelength, l = 7.0 × 10 m.
–7
What is the number of photons emitted per second?

Solution
https://bit.
ly/34HxegP
Step 1: Step 2: Step 3: Step 4:
Identify the Identify the Identify the Solve the problem
problem information given formula to be used numerically

1 Number of photons emitted per second, n 3 P = nhc
l
Then, n = Pl
–7
2 Wavelength, l = 7.0 × 10 m hc
Power, P = 50 W
Planck’s constant, h = 6.63 × 10 J s 4 n = 50 × 7.0 × 10 –7 8
–34
–34
Speed of light in vacuum, c = 3.00 × 10 m s –1 6.63 × 10 × 3.00 × 10
8
= 1.76 × 10 s –1
20
232
7.1.4 LS 7.1.4 7.1.5