A red laser pointer emits light at a wavelength of 488 nm. If the laser emits 7.5  10–4 J of energy per second in the form of visible radiation, how many photons per second are emitted from the laser?
a)
4.1  10–19 photons/sec
b)
5.4  10–16 photons/sec
c)
8.9  1014 photons/sec
d)
1.8  1015 photons/sec
e)
2.5  1018 photons/sec

Answers

Answer 1

The answer to the question, how many photons per second are emitted from the laser is d. 1.84 × 10¹⁵ photons/sec

Since the red laser pointer emits light of wavelength 488 nm, we need to find the energy of each photon from

E = hc/λ where h = Planck's constant = 6.63 × 10⁻³⁴ Js, c = speed of light = 3 × 10⁸ m/s and λ = wavelength of light = 488 nm = 488 × 10⁻⁹ m

Substituting the values of the variables into the equation, we have

E = hc/λ

E = 6.63 × 10⁻³⁴ Js × 3 × 10⁸ m/s ÷ 488 × 10⁻⁹ m

E = 19.89 × 10⁻²⁶ Jm ÷ 488 × 10⁻⁹ m

E = 0.04076 × 10⁻¹⁷ J per photon

E = 4.076 × 10⁻¹⁹ J per photon

Since the laser emits 7.5 × 10⁻⁴ J per second, the number of photons emitted from the laser per second = energy per second/energy per photon

= 7.5 × 10⁻⁴ J per second ÷ 4.076 × 10⁻¹⁹ J per photon

= 1.84 × 10¹⁵ photons/sec

The answer to the question, how many photons per second are emitted from the laser is d. 1.84 × 10¹⁵ photons/sec

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Related Questions

Ammonia will decompose into nitrogen and hydrogen at high temperature. Calculate the pressure equilibrium constant for the decomposition of ammonia at the final temperature of the mixture

Answers

Answer:

Kp = P (N₂) . P³ (H₂)  /  P² (NH₃)

Explanation:

The reaction for the decomposition of ammonia is given by;

2NH₃ (g) ⇌ N₂ (g) + 3H₂ (g)

The pressure equilibrium constant gives the ratio of the pressure of the product over reactants for a reaction that is at equilibrium.

The pressures of the species are raised to the powers of their respective coefficients.

In this reaction;

Products =  N₂ (g) + 3H₂ (g)

Reactant = 2 NH₃ (g)

The pressure equilibrium constant (Kp) is given as;

Kp = P (N₂) . P³ (H₂)  /  P² (NH₃)

write down any four uses of solution






.I will mark him\her as brilliant

Answers

Answer:

because it will help u

because it will make u to understand the question very well

heyyy Powerpuff girls! what advantage does globe maps have over a flat map?

Answers

Answer:

The advantage of the globe is that it promotes visual accuracy. Students need to use a globe frequently if they are to form accurate mental maps. The advantage of the world map is that you can see the entire world at one time. The disadvantage is that world maps distort shape, size, distance, and direction.

Explanation:

miss girl- you could've just looked this up

(just make it look like you typed it)

Answer:

The advantage of the globe is that it promotes visual accuracy. Students need to use a globe frequently if they are to form accurate mental maps. The advantage of the world map is that you can see the entire world at one time. The disadvantage is that world maps distort shape, size, distance, and direction.

Friend?

calculate the packing efficiency of simple cubic unit cell.​

Answers

Answer:

52.4%

Explanation:

Since a simple cubic unit cell contains only 1 atom. The packing efficiency of the simple cubic cell is 52.4 %

The diagram represents a plant leaf cell and two different molecules used in the process of photosynthesis. Molecule 1 and 2 are most likely

A. Carbon dioxide and water
B. Nitrogen and water
C. carbon dioxide and nitrogen
D. Nitrogen and oxygen

Answers

A! Hope that helps :))

How many moles of zinc are there in 0.890 g of zinc?

Answers

Answer:

There are  

4.517

10

23

atoms of Zn in 0.750 mols of Zn.

Explanation:

Since we know that there are  

6.022

10

23

atoms in every mole of a substance (Avogadro's Number), there are  

6.022

E

23

0.750

atoms of Zn in 0.750 mols of Zn.

Answer:

There are  4.517 ⋅ 10  23 atoms of Zn in 0.750 mols of Zn. have a good day:)

Explanation:

What volume (in liters) of a 1.772 M BaCl2 solution is needed to obtain 123 g of BaCl2?

Answers

Answer:

Volume required = 0.327 L

Explanation:

Given data:

Volume in L = ?

Molarity of solution = 1.772 M

Mass of BaCl₂ = 123 g

Solution:

First of all we will calculate the number of moles of BaCl₂,

Number of moles = mass/molar mass

Number of moles = 123 g/ 208.23 g/mol

Number of moles = 0.58 mol

Now, given problem will solve by using molarity formula.

Molarity = number of moles / volume in L

1.772 M = 0.58 mol / Volume in L

Volume in L = 0.58 mol  / 1.772 M

Volume in L = 0.327 L

you take 295.5 g of a solid at 30.0 c and let it melt in 425 g of water. the water temperature decreases from 85.1 c to 30.0 c. calculate the heat of fusion of this solid

Answers

Answer:

[tex]\Delta _{fus}H=332 \frac{J}{g}[/tex]

Explanation:

Hello!

In this case, since the heat of fusion of a solid substance stands for the energy required to melt it, which is a phase transition from solid to liquid, we can see that the heat lost by water is that gained by the solid, so we can write:

[tex]Q_{solid}=-Q_{w}[/tex]

Thus, by using the water data and its specific heat (4.184), we obtain:

[tex]Q_{solid}=-m_{w}C_{w}(T_f-T_i)\\\\Q_{solid}=-425g*4.184\frac{J}{g\°C}*(30.0-85.1)\°C\\\\ Q_{solid}=97,978.82J=98.0kJ[/tex]

Next, since the heat of fusion of a substance is usually represented in terms of energy per amount of substance, we use the mass of solid to obtain:

[tex]\Delta _{fus}H=\frac{98.0kJ}{295.5g}\\\\ \Delta _{fus}H=0.332\frac{kJ}{g}=332 \frac{J}{g}[/tex]

Best regards!

The heat of fusion of the solid is 0.332 KJ/g or 332 J/g

We'll begin by calculating the heat loss by the water. This can be obtained as follow:

Mass of water (M) = 425 g

Initial temperature of water (T₁) = 85.1 °C

Final temperature (T₂) = 30 °C

Change in temperature (ΔT) = T₂ – T₁ = 30 – 85.1 = –55.1 °C

Specific heat capacity of water (C) = 4.184 J/gºC

Heat loss (Q) =?

Q = MCΔT

Q = 425 × 4.184 × –55.1

Q = –97978.82 J

Divide by 1000 to express in KJ

Q = –97978.82 / 1000

Q = –97.98 KJ

Finally, we shall determine the heat fusion of the solid.

Heat loss by water = –97.98 KJ

Heat gained by the solid (Q) = 97.98 KJ

Mass of solid (m) = 295.5 g

Heat of fusion (Hf) =?

Q = m•Hf

97.98 = 295.5 × Hf

Divide both side by 295.5

Hf = 97.98 / 295.5

Hf = 0.332 KJ/g or 332 J/g

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