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2 years ago

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If the work function of a material is such that red light of wavelength 700 nm just barely initiates the photoelectric effect, w

hat must the maximum kinetic energy of ejected electrons be when violet light of wavelength 400 nm illuminates the material? Express your answer with the appropriate units.

1 answer:

marishachu [46]2 years ago

3 0

Answer:

2.13 x 10^-19 J or 0.53 eV

Explanation:

cut off wavelength, λo = 700 nm = 700 x 10^-9 m

λ = 400 nm = 400 x 10^-9 m

Use the energy equation

$E = \frac{h c}{\lambda _{o}}+K$

Where, K be the work function

$\frac{h c}{\lambda} = \frac{h c}{\lambda _{o}}+K$

$K =hc\left ( \frac{1}{\lambda } -\frac{1}{\lambda _{0}}\right )$

$K =6.63\times 10^{-34}\times 3\times 10^{8}\left ( \frac{1}{4\times 10^{-7} } -\frac{1}{7\times 10^{-7}}\right )$

K = 2.13 x 10^-19 J

K = 0.53 eV

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Before the engines fail, the rocket's altitude at time <em>t</em> is given by

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Solve for <em>t</em> to find this time to be

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When it's in freefall, the rocket's altitude is given by

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So the rocket is in motion for a total of 11.2 s + 32.6 s = 43.4 s.

(b) Recall that

${v_f}^2-{v_i}^2=2a\Delta y$

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That is, the rocket has a velocity of 196 m/s in the downward direction as it hits the ground.

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Answer:

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Put the value into the formula

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Answer:

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Explanation:

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An object is launched with an initial speed of 30 m/s at an angle of 60° above the horizontal . What is the maximum height reach

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Answer:

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Explanation:

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