In compliance with conservation of energy, Einstein explained that in the photoelectric effect, the energy of a photon (hv) absorbed by a metal is the sum of the work function (Φ), the minimum energy needed to dislodge an electron from the metal’s surface, and the kinetic energy (Ek) of the electron: hv = Φ + Ek. When light of wavelength 358.1 nm falls on the surface of potassium metal, the speed (u) of the dislodged electron is 6.40 x 10⁵ m7s. (a) What is Ek (½mu²) of the dislodged electron? (b) What is Φ (in J) of potassium?

Answers

Answer 1
Answer:

Answer:

 a) 1.866 × 10 ⁻¹⁹ J      b)   3.685 × 10⁻¹⁹ J

Explanation:

the constants involved are

h ( Planck constant) = 6.626 × 10⁻³⁴ m² kg/s

Me of electron = 9.109 × 10 ⁻³¹ kg

speed of light = 3.0 × 10 ⁸ m/s

a) the Ek ( kinetic energy of the dislodged electron) = 0.5 mu²

Ek = 0.5 × 9.109 × 10⁻³¹ × ( 6.40 × 10⁵ )² = 1.866 × 10 ⁻¹⁹ J

b) Φ ( minimum energy needed to dislodge the electron ) can be calculated by this formula

hv =   Φ + Ek

where Ek = 1.866 × 10 ⁻¹⁹ J

v ( threshold frequency ) = c / λ where c is the speed of light and λ is the wavelength of light = 358.1 nm = 3.581 × 10⁻⁷ m

v = ( 3.0 × 10 ⁸ m/s ) / (3.581 × 10⁻⁷ m ) = 8.378 × 10¹⁴ s⁻¹

hv = 6.626 × 10⁻³⁴ m² kg/s ×  8.378 × 10¹⁴ s⁻¹ = 5.551 × 10⁻¹⁹ J

5.551 × 10⁻¹⁹ J = 1.866 × 10 ⁻¹⁹ J + Φ

Φ = 5.551 × 10⁻¹⁹ J - 1.866 × 10 ⁻¹⁹ J = 3.685 × 10⁻¹⁹ J


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apparently not He is trying to increase his accuracy but not his precision.

Answers

Boyd is most likely trying to increase his accuracy but not his precision. Therefore, option A is correct.

What are accuracy and precision?

Accuracy and precision can be described as two measures of observational error. Accuracy can be defined as how close a given set of measurements, are to their true value, while precision can be defined as how close the measurements are with respect to each other.

In other words, precision can be considered a description of random errors, as well as a measure of statistical variability. Accuracy is a description of systematic errors while low accuracy can bring a difference between a result and a true value.

Accuracy as describing a combination of both kinds of observational error, so high accuracy needs both high precision and high trueness.

In simpler terms, given a set of data points from repeated measurements of the same amount, the sample can be said to be accurate if its average is close to the true value being measured.

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Answer:

The answer is D) He is trying to increase his accuracy and precision.

Explanation:

edg2020

hope this helped :)

A 25.0mL solution acetic acid (CH3CO2H) is titrated with 0.20M NaOH and reaches the endpoint after the addition of 16.3mL of NaOH. What is the concentration of acetic acid in solution

Answers

Answer: 0.1304M

Explanation: Please see the attachments below

Final answer:

The concentration of acetic acid in the solution is 0.1304 M.

Explanation:

To determine the concentration of acetic acid in solution, we can use the concept of stoichiometry and the balanced chemical equation for the reaction between acetic acid and sodium hydroxide. The balanced equation is:

CH3CO2H + NaOH -> CH3CO2Na + H2O

From the balanced equation, we can see that 1 mole of acetic acid reacts with 1 mole of sodium hydroxide. In order to calculate the moles of acetic acid, multiply the volume of NaOH used (16.3 mL) by the molarity of NaOH (0.20 M), then divide the result by 1000 to convert mL to L:

Moles of acetic acid = (16.3 mL NaOH x 0.20 M NaOH) / 1000 = 0.00326 moles

Now, to calculate the concentration of acetic acid in the solution, we divide the moles of acetic acid by the volume of the solution in litres:

Concentration of acetic acid = (0.00326 moles) / (25.0 mL x 1 L/1000 mL) = 0.1304 M

This means that the concentration of the acetic acid in the solution is 0.13M.

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(01.04 LC)What phase of matter has particles that are held together but can flow past each
other and takes the shape of a container, filling it from the bottom up? (3 points)
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Answers

the answer is liquid ! hope this helped :)

Of the following, which element has the highest first ionization energy?Li
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Answers

There are free tutor on my website just got to freetutor.com
I think it’s Li but I don’t totally know

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Answers

Increasing distance between the objects factor will cause the gravitational force between two objects to decrease. Therefore, option B is correct.

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The gravitational force grows in proportion to the size of the masses . The gravitational force weakens rapidly as the distance between masses grows. Unless at least one of the objects has a lot of mass, detecting gravitational force is extremely difficult.

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The force of gravity is proportional to the masses of the two objects and inversely proportional to the square of the distance between them. This means that the force of gravity increases with mass but decreases as the distance between objects increases.

Thus, option B is correct.

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Answer:

B

Explanation:

If a large marshmallow has a volume of 2.75 in3 and density of 0.242 g/cm3, how much would it weigh in grams? 1 in3=16.39 cm3.

Answers


•   
Volume of the marshmallow:

V = 2.75 in^3          (but, 1 in^3 = 16.39 cm^3)

V = 2.75 × 16.39 cm^3

V = 2.75 × 16.39 cm^3

V = 45.0725 cm^3


•   Density:

d = 0.242 g/cm^3


•  Mass:

m = d × V

m = (0.242 g/cm^3) × (45.0725 cm^3)

m = (0.242 g/cm^3) × (45.0725 cm^3)

m = 10.907545 g

m ≈ 10.9 g   <———  this is the answer.


I hope this helps. =)

Answer:

9.92g

Explanation:

2.50 in31×16.39 cm31 in3×0.242 gcm3=9.92 g