The excitation of an electron on the surface of a photocell required 5.0 x 10 –27 J of energy. Calculate the wavelength of light that was needed to excite the electron in an atom on the photocell
Answers
h = Planck's Konstant = 6.63 x 10⁻ ³⁴ joule-second
Energy = (h x frequency) = (h c / wavelength)
Wavelength = (h c) / (energy)
Wavelength = (6.63 x 10^-34 joule-sec x 3 x 10^8 meter/sec) / (5 x 10^-27 joule)
= 19.89 x 10^-26 / 5 x 10^-27 = 39.78 meters
This is an astonishing result ! Simply amazing. That wavelength corresponds
to a frequency of about 7.54 MHz, in one of the short-wave radio bands used by
a lot of foreign-broadcast stations.
If the number in the problem is correct, it means that this 'photocell' responds
to any electromagnetic signal at 7.54 MHz or above ... short-wave radio,
commercial FM or TV signals, FRS walkie-talkies, garage-door openers,
Bluetooth thingies, home WiFi boxes, WiFi from a laptop, microwave ovens,
cellphones, any signal from a satellite, any microwave dish, any heat lamp,
flashlight, LED, black light, or X-ray machine. Some "photocell" !
I'm thinking the number given in the problem for the energy of a photon
at the detection threshold of this device must be wrong by several orders
of magnitude.
(But my math is still bullet-proof.)
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An isometry preservesorientationdistancedirection
Answers
Answer:
Chemical engineers develop and design chemical manufacturing processes. They apply the principles of chemistry, biology, physics, and math to answer problems that involve the production of chemicals, fuel, drugs, food, and many products
Explanation:
Answer:
The main role of chemical engineers is to design and troubleshoot processes for the production of chemicals, fuels, foods, pharmaceuticals, and biologicals, just to name a few. They are most often employed by large-scale manufacturing plants to maximize productivity and product quality while minimizing costs
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Answers
1) 12 cm
2) 3 N
Explanation:
1)
The relationship between force and elongation in a spring is given by Hooke's law:
where
F is the force applied
k is the spring constant
x is the elongation
For the spring in this problem, at the beginning we have:
So the spring constant is
Later, the force is tripled, so the new force is
Therefore, the new elongation is
2)
In this second problem, we know that the elongation of the spring now is
From part a), we know that the spring constant is
Therefore, we can use the following equation to find the force:
And substituting k and x, we find:
So, the force to produce an elongation of 6 cm must be 3 N.
Answers
The answer;
In a conductor, the electric current can flow freely; in an insulator, it cannot flow freely.
Electrical conductance is the measure of the ease to pass an electric current through a material. Conductors usually have free electron in their bonds that enable them to carry electric current end to end. The higher the free electrons the higher the conddictivity. Insulators on the other and have no free electrons with this regard. Having free electrons in the structure is mainly determined by the electron configuration of the atoms of the element.
The correct statement is "In a conductor, electric current can flow freely; in an insulator, it cannot flow freely." The correct option is C.
A conductor is a material that allows the flow of electric current due to the presence of free electrons that can move easily. An insulator, on the other hand, is a material that restricts the flow of electric current because its electrons are tightly bound and cannot move freely.
A. Conductors have magnetic fields; insulators do not have magnetic fields.
This statement is not true. Both conductors and insulators can have magnetic fields, depending on the circumstances. The presence or absence of magnetic fields is not a defining characteristic that distinguishes conductors from insulators.
B. Conductors do not have magnetic fields; insulators do have magnetic fields.
This statement is also not true, for the same reasons mentioned above. Both conductors and insulators can have magnetic fields.
D. In a conductor, electric current cannot flow freely; in an insulator, it can flow freely.
This statement is the opposite of the correct option. In a conductor, electric current can flow freely because conductors have a large number of free electrons that are loosely bound to their atoms and are able to move easily in response to an electric field. In contrast, in an insulator, electric current cannot flow freely because insulators have tightly bound electrons that are not free to move, thus hindering the flow of electric current.
Therefore, option C is the correct one as it accurately describes the difference between conductors and insulators based on their ability to allow the flow of electric current.
To learn more about conductors click:
#SPJ6
Answers
So: 8.45x10^-11=6,673x10^-11x0,844x0,844/d^2
d^2=1,78, so finale d=1,33m
Answers
This is a perfect problem to use positive and negative velocities.
Let's call the positive direction the direction that points UP.
Then the negative direction is the one that points down.
The acceleration of gravity on Earth is 9.8 m/s² down. That means
that any object with no forces on it except gravity gains 9.8 m/s of
speed downward every second.
OK. Ready to go to work:
The ball's initial velocity is +(up)20.0 m/s .
Every second after the toss, the ball has -(down)9.8 m/s more velocity.
The ball's velocity after 3 seconds is
+20 + 3(-9.8) =
20 - 29.4 = - 9.4 m/s .
That means it's velocity at that time is 9.4 m/s pointing down.
Answers
Answer:
Ruler. The first tool that can be used to measure length is a ruler. A ruler can be made of metal, wood or plastic. A ruler has linear measurement markings.
Explanation: