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
The rate of Formation of Carbocation mainly depends on two factors'
1) Stability of Carbocation:
The ease of formation of Carbocation mainly depends upon the ionization of substrate. If the forming carbocation id tertiary then it is more stable and hence readily formed as compared to secondary and primary.
2) Ease of detaching of Leaving Group:
The more readily and easily the leaving group leaves the more readily the carbocation is formed and vice versa. In given scenario the carbocation formed is tertiary in all three cases, the difference comes in the leaving group. So, among these three substrates the one containing Iodo group will easily dissociate to form tertiary carbocation because due to its large size Iodine easily leaves the substrate, secondly Chlorine is a good leaving group compared to Fluoride. Hence the order of rate of formation of carbocation is,
R-I > R-Cl > R-F
B > C > A
1) Stability of Carbocation:
The ease of formation of Carbocation mainly depends upon the ionization of substrate. If the forming carbocation id tertiary then it is more stable and hence readily formed as compared to secondary and primary.
2) Ease of detaching of Leaving Group:
The more readily and easily the leaving group leaves the more readily the carbocation is formed and vice versa. In given scenario the carbocation formed is tertiary in all three cases, the difference comes in the leaving group. So, among these three substrates the one containing Iodo group will easily dissociate to form tertiary carbocation because due to its large size Iodine easily leaves the substrate, secondly Chlorine is a good leaving group compared to Fluoride. Hence the order of rate of formation of carbocation is,
R-I > R-Cl > R-F
B > C > A