module. 1. A Blu-Ray player uses a diode laser with a wavelength ofABR = 405 nm, and is reported also to have a power of PBR =5 mW. How many photons does the Blu-Ray laser put out per second? 2. The work function for tungsten (W) is oW= 4.52 eV. What is the longest light wavelength (sometimes referred to as the cutoff wavelength, Ac) that can result in production of a photocurrent? Lesson 2: Radioactive Decay
Particle Theory of Light
The particle theory of light was the proposal made by Newton in 1704 in his treatise Opticks. This is the most basic light theory, in which light is thought to be made up of microscopic particles known as "corpuscles" and that's why this particle theory of light is also named as Corpuscular theory of light.
Stopping Potential
In an experiment conducted by Heinrich Hertz, an apparatus was made where the incident light was made to fall on the metallic plate, it was discovered that metals emit electrons. The surface electrons are bound to metals with a minimum amount of energy and some of the incident photos enter the surface, they undergo collision with the atoms of the metal, they get absorbed and emit energy to an election, making it photoelectron, where the collision between the photons and electrons ejects the electrons out of the metal and with a negatively charged electron, causes photocurrent and when this current passes it creates an electric field where there is a potential difference at the output due to the anode and cathode of the electrode of the apparatus. This study involves the theory of Quantum physics and electromagnetism involving electromagnetic radiation and electromagnetic wave theory.
Quantization of Charges
An electron is a negatively charged subatomic particle either attached to an an atom or sticks to the nucleus of the atom. Electrons exert the negative charge that tries to balance the positive charge of the nucleus.
PROBLEM SOLVING NUMBERS 1 AND 2 ONLY
![metal surface, will the photoelectric effect Be 0USCI TOUT
Using Planck's equation to calculate the energy of the photon:
E=hf
E=(6.626 x 10-34 J s) (3.0x1016 Hz)
E= 2.0x10-17 J
Comparing the energy of the photon to the copper's work function, we can observe that the photon energy is greater:
2.0x10-17 J>7.53x10-19 J
Hence, it is expected to see the ejection of photoelectrons from the surface of copper.
2. What is maximum kinetic energy of the photons ejected (1)?
Using the equation of maximum kinetic energy of the photoelectron using the equation:
KEmax = E- Ø
KEmax = 2.0x10-17 J-7.53x10-19 J
KEmax = 1.9x10-17 J
Therefore, the kinetic energy of each photoelectron is 1.9x10-17 J.
YBUL
Activity 1: Problem Solving
Directions: Analyze the problem below. Show all your solutions on the answer sheet provided for you at the last page of this
module.
1. A Blu-Ray player uses a diode laser with a wavelength of ABR = 405 nm, and is reported also to have a power of PBR = 5 mW.
How many photons does the Blu-Ray laser put out per second?
2. The work function for tungsten (W) is oW= 4.52 eV. What is the longest light wavelength (sometimes referred to as the cutoff
wavelength, Ac) that can result in production of a photocurrent?
Lesson 2: Radioactive Decay
Geologists are able to determine the age of a dinosaur. It is possible to
date biological specimens such as this because (i) ancient materials were more
radioactive than modern ones; (ii) ancient materials were less radioactive than
modern ones; (iii) biological specimens continue to take in radioactive
substances after they die; (iv) biological specimens no longer take in
radioactive substances after they die; (v) more than one of these.
Radioactivity is the phenomenon exhibited by the nuclei of an atom as a result of nuclear instability. It is the spontaneou
breakdown of an atomic nucleus resulting in the release of energy and matter from the nucleus. Some materials contain unstab
isotopes. This means the nucleus is either too big to hold itself together or has too many protons or neutrons. In order to becon
more stable, they can decay by emitting some forms of radiation by an alpha particle, a beta particle or gamma rays. These materia
are called Radioactive. Unstable atoms continue to be radioactive and undergo decay until they lose enough mass/particles that the
become stable. Radioactive decay happens randomly and one could not exactly tell when it would occur. However, if there is enou
sample of radioactive isotopes, we can determine the activity rate of the sample and its half-life.
1. Radioactive Activity, R- the number of decays taking place every
second. In equation form,
23
R= - AN At = AN ; AN = N NO
where N = number of nuclei present at time t, NO= number of nuclei
the decay constant.
The basic unit of activity is the becquerel (Bq) named after
Henri Becquerel, the first man to discover radioactive radiation.
1 Bq
present at t 0, and A
%3D
1 Bq 1 decay/sec
Another unit used in describing the Activity is the Curie (Ci)
defined to be the activity of 1 g of 226Ra, in honor of Marie Curie's work
with radium.
ICI = 3.7x1010Bq](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F6b275d4f-3298-41bf-bd83-0866b35786b7%2Fc004b627-c488-4f4a-a872-99783e858f87%2Fhhdfslk.jpeg&w=3840&q=75)
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