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
ipn [44]
3 years ago
15

Recall from Chapter 1 that a watt is a unit of en- ergy per unit time, and one watt (W) is equal to one joule per second ( J·s–1

). A 100-W incandescent light- bulb produces about 4% of its energy as visible light. Assuming that the light has an average wavelength of 510 nm, calculate how many such photons are emit- ted per second by a 100-W incandescent lightbulb.
Physics
1 answer:
harkovskaia [24]3 years ago
3 0

Answer:

Explanation:

The energy of a photon is given by the equation E_p=h f, where h is the <em>Planck constant</em> and f the frequency of the photon. Thus, N photons of frequency f will give an energy of E_N=N h f.

We also know that frequency and wavelength are related by f=\frac{c}{\lambda}, so we have E_N=\frac{N h c}{\lambda}, where c is the <em>speed of light</em>.

We will want the number of photons, so we can write

N=\frac{\lambda E_N}{h c}

We need to know then how much energy do we have to calculate N. The equation of power is P=E/t, so for the power we have and considering 1 second we can calculate the total energy, and then only consider the 4% of it which will produce light, or better said, the N photons, which means it will be E_N.

Putting this paragraph in equations:

E_N=(\frac{4}{100})E=0.04Pt=(0.04)(100W)(1s)=4J.

And then we can substitute everything in our equation for number of photons, in S.I. and getting the values of constants from tables:

N=\frac{\lambda E_N}{h c}=\frac{(520 \times10^{-9}m) (4J)}{(6.626\times10^{-34}Js) (299792458m/s)}=1.047 \times10^{19}

You might be interested in
Pls help me ill give brainliest
abruzzese [7]

Answer:

c

Explanation:

a, b, and d are examples of moving forward

while c is moving backwards.

4 0
3 years ago
Read 2 more answers
A concave lens can only form a. A. real image. B. reversed image. C. virtual image. D. magnified image.
Umnica [9.8K]
A concave lens can only form a virtual image. The correct option among all the options that are given in the question is the third option or option "C". Concave lenses are mostly thinner in the middle compared to its edges. I hope that this answer has come to your help.
4 0
3 years ago
Read 2 more answers
A steam engine absorbs 4 x 105 J and expels 3.5 x 105 J in each cycle. What is its efficiency?
Wewaii [24]
Input heat, Qin = 4 x 10⁵ J
Output heat, Qout = 3.5 x 10⁵ J

From the first Law of thermodynamics, obtain useful work performed as
W = Qin  -  Qout
     = 0.5 x 10⁵ J

By definition, the efficiency is
η = W/Qin
   = 100*(0.5 x 10⁵/4 x 10⁵)
   = 12.5%

Answer: The efficiency is 12.5%
3 0
3 years ago
What is the unit of velocity ratio and mechanical advantage and why​
alexandr402 [8]
Both don’t have units beacuse they are ratios
8 0
3 years ago
A person is riding on a Ferris wheel. When the wheel makes one complete turn, the net work done on the person by the gravitation
lara31 [8.8K]

Answer:

0

Explanation:

m = Mass of person

g = Acceleration due to gravity = 9.81 m/s²

d = Vertical height from the ground

F = Force = Weight = mg

Net work done would be

W_n=W_{up}+W_{down}\\\Rightarrow W_n=Fdcos180+Fdcos0\\\Rightarrow W_n=-mgd+mgd\\\Rightarrow W_n=0

Hence, the work done on the person by the gravitational force is 0

7 0
3 years ago
Other questions:
  • an object of mass 6000 kg rests on the flatbed of a truck. it is held in place by metal brackets that can exert a maximum horizo
    6·1 answer
  • 1. A fixed pulley is a machine that increases the effort force.
    13·1 answer
  • A block of mass 2.0kg resting on a smooth horizontal plane is acted upon simultaneously by two forces, 10N due to north and 10n
    6·1 answer
  • Find the current that flows in a silicon bar of 10-μm length having a 5-μm × 4-μm cross-section and having free-electron and hol
    11·1 answer
  • Two charges of 15 pC and −40 pC are inside a cube with sides that are of 0.40-m length. Determine the net electric flux through
    12·1 answer
  • If a transparent blue filter is placed over a camera lens, what happens to visible light entering it
    7·1 answer
  • The differences between models and scientific laws and theories.
    11·1 answer
  • To support a tree damaged in a storm, a 12-foot wire is secured from the ground to the tree at a point 10 feet off the ground. T
    8·1 answer
  • Which is the best explanation for his results?
    5·2 answers
  • Write a paragraph using -Multicellular ,Unicellular ,Tissue ,Xylem ,Organ , System In a paragraph
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!