Exam 1 Part 1 Flashcards

(44 cards)

1
Q

Describe the wavelength, energy, and frequency of red light.

A

long wavelength
low energy
low frequency

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2
Q

Describe the wavelength and frequency of UV light.

A

Short wave length
high energy
high frequency

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3
Q

What is the Photoelectric effect?

A

When light hits the surface of metal, particles are ejected, and electrons are emitted

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4
Q

Where do the electrons come from in the Photoelectric effect?

A

They come from the metal which contains atoms -> electons

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5
Q

How much energy do electrons leave with in the Photoelectric effect?

A

It depends on the wavelength of the light

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6
Q

Do metals like to lose electrons and why?

A

No, it takes energy (lowers potential energy)
they only have a finite amount of energy

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7
Q

What is the relationship between E_light and wavelength?

A

E_light is inversely proportional to wavelength (1/lambda)

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8
Q

What is the relationship between E_light and frequency

A

E_light and frequency are directly proportional

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9
Q

What does v stand for?

A

frequency

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10
Q

What does lambda stand for?

A

wavelength

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11
Q

What is the relationship between E_light and intensity?

A

E_light and intensity are directly proportional

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12
Q

What is another word for intensity?

A

brightness

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13
Q

What does psi stand for?

A

work function (constant)

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14
Q

What does the atomic number tell you?

A

protons=electrons

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15
Q

Explain why the photoelectric effect SHOULD “work” if intensity is high enough?

A

Intensity is proportional to energy (E_light)
so it should have overcome the threshold
E_light> Psi

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16
Q

Explain why the photoelectric effect DOESNT ALWAYS “work” if intensity is high enough?

A

only get potential energy iff the frequency is greater than initial frequency
v>v_o

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17
Q

Explain the expectation that KE should increase with intensity.

A

Intensity is proportional to E_light and
KE_e-=E_light-

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18
Q

What is intensity represented by on a wave function graph?

A

amplitude (middle of the graph to ‘hump’

19
Q

Is light one big wave or a bunch of small waves?

A

a bunch of small waves (photons)

20
Q

What does the color of a light determine?

A

The wavelength

21
Q

Describe the relationship between photons and brightness.

A

of photons increase

as brightness increases
#photons increases

22
Q

What are photons?

A

The smallest ‘piece’ of light and the smallest unit of energy for a given wavelength

23
Q

Explain the photoelectric effect in terms of photons.

A

The atom of the metal needs enough photons to get e- to leave

24
Q

What does the variable h stand for?

A

planks constant

25
What does the variable c stand for?
the speed of light
26
What is the definition of brightness?
change in # of photons
27
What is absorption?
Electron in atom gains energy
28
What is emission?
Electron in atom releases energy
29
Is the system happier at ground state or excited state?
The system is happier at ground state because it has a lower energy (delta H)
30
In an energy level diagram, would a red light be the small energy level jump or the largest?
smallest because energy is inverse to wavelength
31
Describe the Bohr Model for H-atom?
tiny e- orbits massive proton imposed quantized energy levels on electron in atom leads to quantized orbital radii predicts locations of spectral lines (lambda)
32
What does the constant l stand for?
angular momentum
33
Negative potential energy is ____.
Attraction
34
Positive potential energy is ____.
repulsion
35
In the Bohr Model: explain what happens to energy as n gets bigger.
As n gets bigger the energy gets closer to 0 and the energy level approaches infinity
36
True/False: In the Borh Model: To move infinitely far away, it take infinite energy.
False, It takes a finite amount of energy to move infinitely far away
37
Describe the 'sign' (+/-) of Energy at n=1 and what happens to it as n increases.
at n=1 Energy is the most negative and get less negative as n increases energy approaches 0
38
What did the Bohr Model not explain?
Variation in spectral line intensity (brightness) Change in spectra (color) in presence of magnetic field Spectra of atoms with 2 or more electrons**
39
Explain the idea of light as it relates to Wave-Particle Duality.
It was classically thought of as a wave but now as a particle because it is individual photons
40
Explain the idea of matter as it relates to Wave-Particle Duality.
Matter can appear as both a particle and a wave (has both properties)
41
What does the constant p stand for?
momentum
42
Who suggested there was wavelength for particles?
DeBroglie
43
Explain the relationship between the size of things and their wavelength.
small things have noticeable wavelengths and large things do not
44