1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Butoxors [25]
3 years ago
5

A light bulb of 200W emits 1.5μm.How many photons are emmited per second.​

Mathematics
1 answer:
Vinvika [58]3 years ago
3 0

Answer:

Step-by-step explanation:

An incandescent light bulb filament is approximated by a black body radiator, and in the case of a 60W bulb the filament temperature is around 2500˚C which is 2870˚K.

There are a couple of standard black body results that we can use. Firstly the total irradiance emitted per unit area of black body is equal to:

Ed=σT4

where σ=5.67×10−8 Wm−2K−4 is the Stephan-Boltzmann constant. For our bulb we get:

Ed=5.67×10−8⋅28704=3.85×106 Wm−2

As this is a 60W bulb then it has a total irradiance of 60W. Therefore the equivalent black body surface area is:

603.85×106=1.56×10−5 m2

which is 15.6mm2 of filament area.

Secondly we have that the total number of photons emitted per second per unit area of black body is equal to:[1]

Qd=σQT3

where σQ=1.52×1015 photons.sec−1m−2K−3. For our bulb this is:

Qd=1.52×1015⋅28703=3.59×1025 photons.sec−1m−2

Multiplying by the bulb’s equivalent black body surface area gives the result we require:

3.59×1025⋅1.56×10−5=5.6×1020 photons/sec

As a sanity check we know that these photons have a total energy of 60 joules per second, so the average energy per photon is:

605.6×1020=1.1×10−19 joules

A photon of wavelength λ has energy E=hcλ, and so the average energy corresponds with a photon of wavelength:

λ=hc1.1×10−19=1.9μm

Here’s a chart of the power distribution by wavelength, with the average photon wavelength shown as the dashed line, and visible wavelengths highlighted:

emember that there are a higher proportion of photons for the longer, lower energy wavelengths, so the average is weighted to the right.

We can also see from the original calculation that the general case is:

QdWEd=σQT3WσT4=2.68×1022WT photons/sec

for a bulb of wattage W watts and filament temperature T ˚K. So the photon emission rate is inversely proportional to the filament temperature. As a somewhat counter-intuitive example, a 60W halogen bulb with 3200˚K filament only emits photons at 90% of the rate of the standard 60W bulb, despite being visibly brighter.

The reason is that as the temperature increases then an increased proportion of shorter wavelength photos are emitted and therefore the average energy per photon increases, decreasing the number emitted per second. However at the same time an increased proportion of the photons are visible rather than infra-red, making the bulb appear brighter. Here’s the power distribution chart with the 60W halogen curve added for comparison:

You might be interested in
Help me as soon as possible PLEASE HELP
disa [49]

Answer:

QRT = 47, TRS = 133

Step-by-step explanation:

Since QRS is a line, QRT + TRS = 180.

QRT+TRS=180\\3x+5+10x-7=180\\

Then, solve for x. Combine like terms.

13x-2=180\\13x=182\\x=14

Then, plug in 14 for x.

1. (3*14+5)\\\\QRT = 47\\\\2. (10*14-7)\\\\TRS = 133

7 0
3 years ago
How to do I solve this
padilas [110]
4. 2b-6+3b=
5b-6=143
5b=143+6
5b=149

b=149
    ------
       5
5 0
3 years ago
Please answer this!) Name each angle in four ways. The classify as acute,right,obtuse or straight. When writings the name write
Rudik [331]

Answer:

B

Step-by-step explanation: ik it is

8 0
3 years ago
An Angle measures 64 more than the measure of its supplementary angle what is the measure of each angle
ValentinkaMS [17]

Answer:

Original angle = 122*

Supplementary angle = 58*

Step-by-step explanation:

A supplementary angle is one of two angles that make up 180*

If one angle is 30*, its supplementary angle is 150*. 30 + 150 = 180.

So in this case we have two angles, the original and the supplementary angle. The original angle is 64* more than the supplementary angle. The key word is MORE.

The formula to figure it out would look like this:  x + (x + 64) = 180

x is the supplementary angle

x + 64 is the original angle (64 MORE than its supplementary angle)

180 is the total measure of the two angles because they are supplementary and we know that supplementary angles always equals 180* when added together.

Take the formula and do a little algebra.

x + (x + 64) = 180

Subtract 64 from both sides

x + x = 116

Combine the x's

2x = 116

Divide both side by 2

x = 58

Remeber we know that the original angle is 64 more than the supplementary angle, so we'll add the 64 to the value of x and we get 122.

x + 64 = 122

Check our work:

x + (x + 64) = 180

58 + 58 + 64 = 180

4 0
3 years ago
If x + 4 = y, then x + 12 =
GrogVix [38]
If x+4=y, then x+12=3y because 4 (3)=12
6 0
3 years ago
Other questions:
  • A company's profit is described by the equation P(x)=-5x^2+300x+15,000
    7·2 answers
  • The sum of 3 consecutive whole numbers is 72
    13·1 answer
  • Please help asap 25 pts
    14·2 answers
  • NEED HELP <br>what is X in the diagram ​
    6·1 answer
  • You bought two tickets to the movies at a price of $7 and six tickets at a price of $5
    8·1 answer
  • Cindy earned 35 bonus points. Farid earned b more bonus points than Cindy. Write an expression that shows how many bonus points
    14·2 answers
  • PLEASE HELP I WILL GIVE BRAINLIEST!
    14·2 answers
  • Which equation can be used to find the measure of the angles below if line a is parallel to line b?
    10·2 answers
  • Triangle ABC and Triangle DEF are similar. Find the unknown measures. (t = ? and u = ?)
    11·1 answer
  • What is the missing length?<br> с<br> 4 mm<br> 3 mm<br> 2<br> area = 10 mm
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!