The human eye is a complex sensing device for visible light. The optic nerve needs a minimum of 2.0 × 10−17 J of energy to trigg
er a series of impulses that eventually reach the brain. How many photons of blue light (475 nm) are needed?
2 answers:
The number of photons needed to get the energy to trigger a series of impulses that eventually reaches the brain is: 48.7 photons
<h3><em>Further explanation</em></h3>
The photoelectric effect is an electron coming out of a metal because of electromagnetic radiation
One type of electromagnetic radiation is light
Electrons can come out of metal because they absorb electromagnetic energy radiated on metals. There is also kinetic energy released from metal, which is according to the equation:
E = hf - hfo
fo = the threshold frequency of electromagnetic waves
Radiation energy is absorbed by photons
The energy in one photon can be formulated as
Where
h = Planck's constant (6,626.10⁻³⁴ Js)
f = Frequency of electromagnetic waves
f = c / λ
c = speed of light
= 3.10⁸
λ = wavelength
Known wavelength 475 nm
475 nm = 475.10⁻⁹ m
We put it in the formula to find this light energy E = h. f
E = h. c /λ
E =: 6,626.10⁻³⁴. 3.10⁸ / 475 .10⁻⁹ m
E = 4.1.10⁻¹⁹
Because this is 1 photon energy, while the minimum energy required is 2.0 × 10⁻¹⁷ J, the number of photons needed is:
number of photons = 2.0 × 10−17 J: 4.1.10⁻¹⁹
number of photons = 48.7
<h3><em>Learn more</em></h3>Electromagnetic radiation with wavelength of 745 nm
The energy of a photon
The equation E = hf
the approximate energy of a photon
The equation for photon energy
the wavelength of a photon whose energy is twice
You might be interested in
Explanation: Electron dot structures are the lewis dot structures which represent the number of valence electrons around an atom in a molecule.
The electronic configuration of potassium is
Valence electrons of potassium are 1.
The electronic configuration of Bromine is
Valence electrons of bromine are 7.
These two elements form ionic compound.
Ionic compound is defined as the compound which is formed from the complete transfer of electrons from one element to another element.
Here, one electron is released by potassium which is accepted by bromine element. In this process, Potassium becomes cation having +1 charge and Bromine become anion having (-1) charge.
The ionic equation follows:
The electron dot structure is provided in the image below.
Core reactions that occur:
¹⁴₇N + ⁴₂He → ¹⁷₈O + ¹₁H
Can be written :
¹⁴₇N (α, H) ¹⁷₈O , α = ⁴₂He
<h3>Further explanation </h3>Fusion and fission reactions are reactions involving atomic nucleus reactions
Fission reaction is a nucleation division reaction by firing a particle usually neutron so that it gets smaller particles of atomic nuclei.
A fusion reaction is a combining reaction of 2 atomic nuclei. Usually what is often used is a reaction between the hydrogen isotope that will form Helium
At the core, the reaction applies the law of eternity
- 1. energy
the energy before and after the reaction is the same
- 2. atomic number
the number of atomic numbers before and after the same
- 3. mass number
the number of mass numbers before and after the same
Particles that play a role in core reactions include
- alpha α particles ₂He⁴
- beta β ₋₁e⁰ particles
- gamma particles γ
- positron particles ₁e⁰
In general, the core reaction equation can be written:
<h3> X + a ---> Y + b + Q </h3>
X = target core
a = particle fired
Y = new core
b = the particle produced
Q = heat energy
or can be written simply
<h3> X (a, b) Y </h3>
In the ¹⁴₇N atomic nucleus, a fusion reaction occurs with ⁴₂He which produces isotopes of Oxygen and ¹₁H protons.
¹⁴₇N + ⁴₂He → ¹⁷₈O + ¹₁H
This reaction can be written down
¹⁴₇N (α, H) ¹⁷₈O
<h3> Learn more </h3>
the half-life of the element Lokium
nuclear decay reaction
Plutonium - 239
Keywords: Fusion and fission reactions, alpha ₂He⁴, nuclei
