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Vlad1618 [11]
3 years ago
12

Pennies are made of zinc coated with copper. Copper has a work function of 4.7 eV. The ozone layer blocks nearly all solar radia

tion with wavelength shorter than 320nm, but a very small amount of 200 nm light still manages to reach the Earth's surface. Can direct sunlight produce photoelectrons from a penny?
Chemistry
1 answer:
Vadim26 [7]3 years ago
4 0

Answer:

yes  it can  λ =265  nm

Explanation:

Here we will use  the relationship

   E = h c/λ  ∴   λ  = E/ hc  where

                                          h= Plank's constant

                                           c= Speed of light

                                           λ = Wavelength = ?

Substituting

note need E in J ,

E = 4.7 eV x 1.602 x 10⁻¹⁹ J/eV = 7.5 x 10⁻¹⁹ J)

λ = 7.5 x 10 ⁻¹⁹ J / (  6.626 x 10⁻³⁴ Js x 3 x 10^8) =  2.65 x 10⁻⁷ m = 2.65

=  2.65 x 10⁻⁷ m x 1 x 10⁹ nm/m = 265 nm

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What does E=mc^2 mean
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E represents units of energy, m represents units of mass, and c2 is the speed of light squared, or multiplied by itself


So I THINK that A is the right answer but i may be wrong.


I hope this helped :)

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What does unsaturated zone mean?
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5) Read each Eco fact. Propose a solution to prevent the environmental problems of the
Aleksandr [31]

Answer:

The creation of regulations that limit timber activities and the exploitation of wood can prevent soil erosion in Troy.

Explanation:

The exploitation of the wood was an intense activity and that did not have any regulation that would limit its damages, caused by its exploratory activities.

As the timber market was totally undisciplined, the exploitation of the wood caused a strong deforestation, leaving the soil totally unprotected and susceptible to strong erosion.

Soil erosion has a very negative impact on the environment, requiring regulations to be made to prevent this from happening.

Based on this, we can say that one way to prevent environmental problems in the seaport of troy is by establishing laws and regulations that limit logging activities.

3 0
2 years ago
The The thermal conductivity of a sheet of rigid, extruded insulation is reported to be k=0.029 W/ m measured temperature differ
vfiekz [6]

Answer:

Heat flux = 13.92 W/m2

Rate of heat transfer throug the 3m x 3m sheet = 125.28 W

The thermal resistance of the 3x3m sheet is 0.0958 K/W

Explanation:

The rate of heat transfer through a 3m x 3m sheet of insulation can be calculated as:

q=-k*A*\frac{\Delta T}{\Delta X}\\\\q=-0.029\frac{W}{m*K}*(3m*3m)*\frac{12K}{0.025m}  =125.28W

The heat flux can be defined as the amount of heat flow by unit of area.

Using the previous calculation, we can estimate the heat flux:

heat \, flux=\frac{q}{A}=\frac{125.28 W}{9 m^{2} }  =13.92 W/m^{2}

It can also be calculated as:

q/A=-k*\frac{\Delta T}{\Delta X}

The thermal resistance can be expressed as

\Delta T=R_t*Q\\R_t=\Delta T/Q=\frac{\Delta X}{k*A}

For the 3m x 3m sheet, the thermal resistance is

R_t = \frac{\Delta X}{k*A}=\frac{0.025m}{0.029W/mK*9m^{2}}=0.0958 \, K/W

4 0
3 years ago
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