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bixtya [17]
3 years ago
9

Estimate the number of photons emitted per second from 1.0 cm2 of a person's skin if a typical emitted photon has a wavelength o

f 10,000 nm. Assume the skin of a person is at the normal body temperature of 37∘C.
Physics
1 answer:
Diano4ka-milaya [45]3 years ago
4 0

Answer:

2.63 x 10^18

Explanation:

A = 1 cm^2 = 1 x 10^-4 m^2

λ = 10,000 nm = 10,000 x 10^-9 m = 10^-5 m

T = 37 degree C = 37 + 273 = 310 k

Energy of each photon = h c / λ

where, h is the Plank's constant and c be the velocity of light

Energy of each photon = (6.63 x 10^-34 x 3 x 10^8) / 10^-5 = 1.989 x 10^-20 J

Energy radiated per unit time = σ A T^4

Where, σ is Stefan's constant

Energy radiated per unit time = 5.67 x 10^-8 x 10^-4 x 310^4 = 0.05236 J

Number of photons per second = Energy radiated per unit time / Energy of  

                                                                                               each photon

Number of photons per second = 0.05236 / (1.989 x 10^-20) = 2.63 x 10^18

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abruzzese [7]
Basic research, also called pure research or fundamental research, is scientific research aimed to improve scientific theories for improved understanding or prediction of natural or other phenomena.

(source: wikipedia)
5 0
3 years ago
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Sunlight is made up of EM waves. True or False
GrogVix [38]

Answer:

true

Explanation:

7 0
3 years ago
What is the density of 53.4 wt queous naoh solution if 16.7 ml of the solution diluted to 2.00 l gives 0.169 m naoh?
vampirchik [111]

The density of 53.4 wt aqueous NaOH solution is 0.809 g/ml

Given data:

  • The mass percent of NaOH is 53.4.
  • Volume of NaOH diluted is 16.7 ml.
  • The volume of diluted solution is 2.00 L =2000 ml.
  • Concentration of diluted solution is 0.169 M.

First, we find the initial concentration of NaOH by using the following formulae,

M₁V₁ = M₂V₂

Where,

M₁ is the initial molarity of NaOH

M₂ is the molarity after dilution

V₁ is the initial volume of NaOH

V₂ is the final volume after dilution.

Substituting the values,

M₁ × 16.7 ml = 0.169 M × 2000 ml,

M₁ =  \frac{0.169 M *2000 ml}{16.7 ml}

M₁ = 20.2 M.

Thus, the initial concentration of NaOH is 20.2 M.

we know, 1 M solution contains 1 mol of substance present in 1 L solution,

Thus, 20.2 M solution will have 20.2 mols of NaOH.

Now, we can find the mass of NaOH by using the number of moles and molar mass.

  • molar mass of NaOH is 40 g/mol.

Mass = no. of moles × molar mass

= 20.2 mol × 40 g/mol

= 808 g.

Thus, the mass of NaOH is 808g.

53.4 wt of NaOH means 53.4 g of NaOH in a 100 g solution,

Thus, 808 g of NaOH will be present in ,

⇒ \frac{53.4 g NaOH}{100 g solution} = \frac{808 g NaOH}{x g solution}

⇒ 1513.1 g

Now, Convert the grams of NaOH to milliliters, using the density of NaOH at room temperature.

  • The density of NaOH at room temperature is 1.515 g/ml,

Density = \frac{mass}{volume}

⇒ 1.515 g/mol = \frac{1513.1 g}{volume}

⇒ volume = \frac{1513.1 g}{1.515 g/mol}

⇒ volume = 998.7 ml.

Thus, the volume of NaOH is 998.7 ml.

Hence, we know,

  • the mass of NaOH is 808 g
  • the volume of NaOH is 998.7 ml

Substituting the values,

Density = 808 g / 998.7 g/ml

⇒ Density = 0.809 g/ml

Thus, the density of 53.4 wt aqueous NaOH is 0.809 g/ml.

To learn more about Density here

brainly.com/question/15164682

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3 0
2 years ago
The inner and outer surfaces of a cell membrane carry a negative and positive charge respectively. Because of these charges, a p
padilas [110]

Answer:

The magnitude of the electric field inside the membrane is 8.8×10⁶V/m

Explanation:

The electric field due to electric potential at a distance Δs is given by

E=ΔV/Δs

We have to find the magnitude electric field in the membrane

Ecell= -ΔV/Δs

E_{cell}=-\frac{V_{in}-V_{out}}{s} \\E_{cell}=\frac{V_{out}-V_{in}}{s}\\E_{cell}=\frac{0.070V}{8*10^{-9}m } \\E_{cell}=8.8*10^{6}V/m

The magnitude of the electric field inside the membrane is 8.8×10⁶V/m

6 0
3 years ago
a flat bed truck is carrying a crate up a 10.0 hill inn the picture. the coefficent of the static friction between the truck bed
almond37 [142]

Answer:

a = 0.711 m/s^2

Explanation:

As we know that truck is moving up the hill

So here we have two forces on the crate placed on the truck

1) gravitational force along the floor

2) Friction force along the floor

Now here if the truck is moving with maximum possible acceleration so that there is no slipping of the crate

So here we will have

\mu mg cos\theta - mgsin\theta = ma

a = \mu g cos\theta - g sin\theta

a = (0.25)(9.81)cos10 - 9.81 sin10

a = 0.711 m/s^2

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4 years ago
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