**How many photons are contained in a flash of green light (525 nm) that contains 189 kj of energy? give your answer to 2 significant figures and in scientific notation.**

(1) **4.99×10^23**

(2) 7.99×10^30

(3) 5.67×10^23

(4) 1.25×10^31

(5) 3.75×10^23

**=** **4.99e23** **Photons**

**Explanation:**

We know,

c = f λ (Equation 1)

Here,

c = speed of light (m/s)

f= frequency (Hz)

λ = wavelength (m)

E=h f (Equation 2)

Here,

E= energy (J) ;

h = Planck’s constant [ 6.62607004 × 10^{-34} J*s ]

Substitute Equation 1 into Equation 2 using frequency

E = (hc)/λ

= (6.62607004 × 10^{-34} × 3 ×10^{8}) / 525 × 10^{-9}

= 3.7863257× 10^{-19} J/photon

E = 3.7863257× 10^{-22} kJ/photon [Divide by 1000 to get kJ/photon]

Now, We have E = 189 kJ of energy,

Dividing 189 kJ by 3.7863257× 10^{-22} kJ/photon , the kJ term cancels and we get

**the** **number of photons** **= 4.9916467× 10 ^{23}**

**Photons,**or

= **4.99 × 10 ^{23}**

**Photons**

Hope you have understood the solution to the problem,

“* How many photons are contained in a flash of green light (525 nm) that contains 189 kj of energy?*”

**The answer is 4.99e23**

**Photons**

For more practice, you may check the following problems.

## Problems related to ” How many photons are contained in a flash of * light that contains * kJ of energy?”

You may jump to the specific problem by clicking any of them of the list.

- How many photons are contained in a flash of green light (525 nm) that contains 273 kJ of energy?
- How many photons are contained in a burst of green light (525 nm) that contains 125 kJ of energy?
- How many photons are contained in a flash of blue light (454 nm) that contains 50.0 kJ of energy?
- How many photons are contained in a flash of blue light (485 nm) that contains 369 kJ of energy? Give your answer to 2 significant figure and in scientific notation.
- How many photons are contained in a flash of orange light (605 nm) that contains 230 kj of energy? give your answer to 2 significant figures and in scientific notation.
- How many photons are contained in a flash of yellow light (575 nm) that contains 277 kj of energy? give your answer to 2 significant figures and in scientific notation.
- How many photons are contained in a flash of violet light (425 nm) that contains 140 kj of energy? give your answer to 2 significant figures and in scientific notation.

**How many photons are contained in a flash of green light (525 nm) that contains 273 kJ of energy?**

Answer: **7.21e23** Photons

**Explanation:**

We know,

c = f λ (Equation 1)

Here,

c = speed of light (m/s)

f= frequency (Hz)

λ = wavelength (m)

E=h f (Equation 2)

Here,

E= energy (J) ;

h = Planck’s constant [ 6.62607004 × 10^{-34} J*s ]

Substitute Equation 1 into Equation 2 using frequency

E=(hc)/λ

= (6.62607004 × 10^{-34} × 3 ×10^{8}) / 525 × 10^{-9}

= 3.7863257× 10^{-19} J/photon

E = 3.7863257× 10^{-22} kJ/photon [Divide by 1000 to get kJ/photon]

Now, We have E = 273 kJ of energy,

Dividing 273 kJ by 3.7863257× 10^{-22} kJ/photon , the kJ term cancels and we get

the **number of photons =** **7.2101563× 10 ^{23} **

**= 7.21 × 10 ^{23}**

**photons**

## How many photons are contained in a burst of green light (525 nm) that contains 125 kJ of energy?

**The number of photons is** **7.301e23**

Here,

E = 125 KJ of Energy

Simply, dividing 125 kJ by 3.7863257× 10^{-22} kJ/photon , the kJ term cancels and we get

**7.301 × 10 ^{23}** photons

**How many photons are contained in a flash of blue light (454 nm) that contains 50.0 kJ of energy?**

**=** **1.14e23** **Photons**

We know,

c = f λ (Equation 1)

Here,

c = speed of light (m/s)

f= frequency (Hz)

λ = wavelength (m)

E=h f (Equation 2)

Here,

E= energy (J) ;

h = Planck’s constant [ 6.62607004 × 10^{-34} J*s ]

Substitute Equation 1 into Equation 2 using frequency

E=(hc)/λ

= (6.62607004 × 10^{-34} × 3 ×10^{8}) / 454 × 10^{-9}

= 4.3784604× 10^{-19} J/photon

E = 4.3784604× 10^{-22} kJ/photon [Divide by 1000 to get kJ/photon]

Now, We have E = 50 kJ of energy,

Dividing 50 kJ by 4.3784604× 10^{-22} kJ/photon , the kJ term cancels and we get

the **number of photons** = **1.1419539× 10 ^{23} **

**= 1.14 × 10 ^{23}**

**Photons**

**are contained in the flash of blue light**.

## How many photons are contained in a flash of blue light (485 nm) that contains 369 kJ of energy? Give your answer to 2 significant figure and in scientific notation.

**9.00e23** **Photons** **are contained in the flash of blue light**.

We know,

c = f λ (Equation 1)

Here,

c = speed of light (m/s)

f= frequency (Hz)

λ = wavelength (m)

E=h f (Equation 2)

Here,

E= energy (J) ;

h = Planck’s constant [ 6.62607004 × 10^{-34} J*s ]

Substitute Equation 1 into Equation 2 using frequency

E=(hc)/λ

= (6.62607004 × 10^{-34} × 3 ×10^{8}) / 485 × 10^{-9}

= 4.0986× 10^{-19} J/photon

E = 4.0986× 10^{-22} kJ/photon [Divide by 1000 to get kJ/photon]

Now, We have E = 369 kJ of energy,

Dividing 369 kJ by 4.3784604× 10^{-22} kJ/photon , the kJ term cancels and we get

**The number of photons** **is** **9.0030742× 10 ^{23} **

Now,** the number of photons up to two significant figures in scientific notation is** **9.00 × 10 ^{23}**

**Photons**

## More Problems on “How many photons are contained in a flash of light”

### How many photons are contained in a flash of orange light (605 nm) that contains 230 kj of energy? give your answer to 2 significant figures and in scientific notation.

A generalized formula, number of Photons = E/(hc/λ ), Here, take E in Joule. i.e 230 kJ = 230 x 10^{3} J

**The number of photons** **is ** **7.00 × 10 ^{23}**

**Photons**

### How many photons are contained in a flash of yellow light (575 nm) that contains 277 kj of energy? give your answer to 2 significant figures and in scientific notation.

A generalized formula, number of Photons = E/(hc/λ ), Here, take E in Joule. i.e 277 kJ = 277 x 10^{3} J

**The number of photons** **is ** **8.01 × 10 ^{23}**

**Photons**

### How many photons are contained in a flash of violet light (425 nm) that contains 140 kj of energy? give your answer to 2 significant figures and in scientific notation.

A generalized formula, number of Photons = E/(hc/λ ), Here, take E in Joule. i.e 140 kJ = 140 x 10^{3} J

**The number of photons** **is ** **2.99 × 10 ^{23}**

**Photons**

## Glossary for “**How many photons are contained in a flash of green light**” type problems

### What is a photon?

In simple words, Photon is a small discrete amount of electromagnetic radiation. Photon is the basic unit of all lights. In other words, the photon is a type of elementary particle which is the quantum of the electromagnetic field including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they always move at the speed of light in a vacuum, 299792458 m/s or 3 ×10^{8} m/s (approx.). [Source: Wikipedia].

### What is Energy?

In simple words, **Energy is the ability to do work**.

In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object. Energy is a conserved quantity; the law of conservation of energy states that energy can be converted in form, but not created or destroyed. [Source: Wikipedia].

The unit of Energy is Joule (J).

### What is Plank’s Constant?

The Planck constant, or Planck’s constant, is the quantum of electromagnetic action that relates a photon’s energy to its frequency. The Planck constant multiplied by a photon’s frequency is equal to a photon’s energy. [Source: Wikipedia].

Plank’s Constant is 6.62607004 × 10^{-34} m^{2} kg / s or J*s

#### What is Planck’s constant used for?

Plank’s constant is used to describe the behavior of waves and particles on the atomic scale, including the particle aspect of light.

#### What is the wavelength of Green Light?

The **wavelength of green light is 525 nm.**

## List of problems solved related to ” How many photons are contained in a flash of * light that contains * kJ of energy?”

- How many photons are contained in a flash of green light (525 nm) that contains 189 kj of energy? give your answer to 2 significant figures and in scientific notation.
- How many photons are contained in a flash of green light (525 nm) that contains 273 kJ of energy?
- How many photons are contained in a burst of green light (525 nm) that contains 125 kJ of energy?
- How many photons are contained in a flash of blue light (454 nm) that contains 50.0 kJ of energy?
- How many photons are contained in a flash of blue light (485 nm) that contains 369 kJ of energy? Give your answer to 2 significant figure and in scientific notation.
- How many photons are contained in a flash of orange light (605 nm) that contains 230 kj of energy? give your answer to 2 significant figures and in scientific notation.
- How many photons are contained in a flash of yellow light (575 nm) that contains 277 kj of energy? give your answer to 2 significant figures and in scientific notation.
- How many photons are contained in a flash of violet light (425 nm) that contains 140 kj of energy? give your answer to 2 significant figures and in scientific notation.

Hope, you’ve understood the solutions. All the problems are similar. If you solve the first one carefully, you’ll be able to solve the rest of the problems. Check more such problems here.