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
chubhunter [2.5K]
3 years ago
15

The human eye can respond to as little as 10^−18 J of light energy. For a wavelength at the peak of visual sensitivity, 550 nm,

how many photons lead to an observable flash?
Physics
2 answers:
Bumek [7]3 years ago
7 0
<span>The key equation is going to come from Mr Planck: E=h \nu

Where h is Plancks constant; and ν is the frequency. This equation gives you the energy per photon at a given frequency. Alas, you're given wavelength, but that's easy enough to convert to frequency given the following equation:

c= lambda / nu

where c is the speed of light; λ (lambda) is the wavelength; and ν is again frequency. As soon as you know the energy of a photon with a wavelength of 550nm, you should know how many photons you would require to accumulate 10^-18J. Be careful with your units.</span>
Kaylis [27]3 years ago
6 0

Answer:

3 photons

Explanation:

The energy of a photon (E) can be calculated by the expression:

E = h*c/λ

Where h is the Planck constant (6.63x10⁻³⁴ J.s), λ is the wavelength (550 nm = 5.50x10⁻⁷m), and c is the speed of the light (3.00x10⁸ m/s).

E= (6.63x10⁻³⁴ * 3.00x10⁸)/(5.50x10⁻⁷)

E = 3.62x10⁻¹⁹ J

Which is the energy of one photon. The human eye can respond to 10⁻¹⁸ J, so:

1 photon ------------------------ 3.62x10⁻¹⁹ J

x              ----------------------- 10⁻¹⁸ J,

By a simple direct three rule

x = 2.76 ≅ 3 photons.

You might be interested in
Suppose you apply a force of 75 N to a 25-kg object. What will the acceleration of the object be?
Serjik [45]

Answer:

I belive it would be ture

Explanation:

It's been a while since I learned this but I think that is right.

6 0
3 years ago
Read 2 more answers
If you decrease the length of a wire, what effect will it have on resistance
attashe74 [19]
As the length increases, resistance increases, as a result current decreases.
7 0
4 years ago
A ball is released from the top of a tower of height h meters. it takes T seconds to reach the ground . what is the position of
alekssr [168]

Answer:the

8/9 h

Explanation:

Height  =   1/2 a T^2     now change to T/3

 now height = 1/2 a (T/3)^2   =<u> 1/9</u>  1/2 a T^2     <===== it is 1/9 of the way down   or   8/9 h

 

3 0
2 years ago
An N-slit system has slit separation d and slit width a. Plane waves with intensity I and wavelength O are incident normally on
Leokris [45]

Answer:

E. d and O

Explanation:

"Light passing through a single slit forms a diffraction pattern somewhat different from those formed by double slits or diffraction gratings".

According to Huygens’s principle, "for each element of the wavefront in the slit emits wavelets. These are like rays that start out in phase and head in all directions. (Each ray is perpendicular to the wavefront of a wavelet.) Assuming the screen is very far away compared with the size of the slit, rays heading toward a common destination are nearly parallel".

The destructive interference for a single slit is given by:

d sin \theta = m\lambda , m=1,-1,2,-2,3,...

Where

d is the slit width

\lambda=O is the light's wavelength

\theta is the angle relative to the original direction of the light

m is the order od the minimum

I represent the intensity

When the intensity and the wavelength are incident normally the angular as we can see on the expression above the angular separation just depends of the distance d and the wavelength O.

7 0
3 years ago
A radar station detects an airplane approaching directly from the east. At first observation, the range to the plane is 375.0 m
Gekata [30.6K]

Answer:

819.78 m

Explanation:

<u>Given:</u>

  • OA = range of initial position of the airplane from the point of observation = 375 m
  • OB = range of the final position of the airplane from the point of observation = 797 m
  • \theta = angle of the initial position vector from the observation point = 43^\circ
  • \alpha = angle of the final position vector from the observation point = 123^\circ
  • \vec{AB} = displacement vector from initial position to the final position

A diagram has been attached with the solution in order to clearly show the position of the plane.

\vec{OA} = OA\cos \theta \hat{i}+OA \sin \theta \hat{j}\\\Rightarrow \vec{OA} = 375\ m\cos 43^\circ \hat{i}+375\ m\sin 43^\circ \hat{j}\\\Rightarrow \vec{OA} = (274.26\ \hat{i}+255.75\ \hat{j})\ m\\\vec{OB} = OB\cos \alpha \hat{i}+OB \sin \alpha \hat{j}\\\Rightarrow \vec{OB} = 797\ m\cos 123^\circ \hat{i}+797\ m\sin 123^\circ \hat{j}\\\Rightarrow \vec{OB} = (-434.08\ \hat{i}+668.42\ \hat{j})\ m

Displacement vector of the airplane will be the shortest line joining the initial position of the airplane to the final position of the airplane which is given by:

\vec{AB}=\vec{OB}-\vec{OA}\\\Rightarrow \vec{AB} =  (-434.08\ \hat{i}+668.42\ \hat{j})\ m-(274.26\ \hat{i}+255.75\ \hat{j})\ m\\\Rightarrow \vec{AB} =  (-708.34\ \hat{i}+412.67\ \hat{j})\ m

The magnitude of the displacement vector = \sqrt{(-708.34)^2+(412.67)^2}\ m = 819.78\ m

Hence, the magnitude of the displacement of the plane is 819.67 m during the period of observation.

8 0
3 years ago
Other questions:
  • Why can light microscopes produce images in their natural color
    6·1 answer
  • What happens during the apparent retrograde motion of a planet?
    14·1 answer
  • 3. A 64 lb weight stretches a spring 4 ft in equilibrium. The weight is initially displaced 6 inches above equilibrium and given
    15·1 answer
  • What does a measured number tell you?
    12·1 answer
  • How many mL beakers would be when seprating salt,sand,iron fillings,and beads
    13·1 answer
  • Is hydrogen good conductor or poor conductor
    11·2 answers
  • Which is the correct equation for the force applied by a spring?
    8·1 answer
  • Which of the following is NOT a characteristic of noble gases?
    7·2 answers
  • Compare and contrast climate and weather
    15·2 answers
  • Plz help I will mark as brainlest plz help me
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!