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4 years ago

Violet light has a wavelength of 4.10X10-12m what is the frequency

1 answer:

3 0

The relation between frequency and wavelength is:

$\nu = \frac{c}{\lambda} = \frac{3\cdot 10^8\ m/s}{4.1\cdot 10^{-12}\ m} = \bf 7.32\cdot 10^{19}\ s^{-1}$

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The following table lists the work functions of a few common metals, measured in electron volts. Metal Φ(eV) Cesium 1.9 Potassiu

Citrus2011 [14]

A. Lithium

The equation for the photoelectric effect is:

$E=\phi + K$

where

$E=\frac{hc}{\lambda}$ is the energy of the incident light, with h being the Planck constant, c being the speed of light, and $\lambda$ being the wavelength

$\phi$ is the work function of the metal (the minimum energy needed to extract one photoelectron from the surface of the metal)

K is the maximum kinetic energy of the photoelectron

In this problem, we have

$\lambda=190 nm=1.9\cdot 10^{-7}m$ , so the energy of the incident light is

$E=\frac{hc}{\lambda}=\frac{(6.63\cdot 10^{-34}Js)(3\cdot 10^8 m/s)}{1.9\cdot 10^{-7} m}=1.05\cdot 10^{-18}J$

Converting in electronvolts,

$E=\frac{1.05\cdot 10^{-18}J}{1.6\cdot 10^{-19} J/eV}=6.5 eV$

Since the electrons are emitted from the surface with a maximum kinetic energy of

K = 4.0 eV

The work function of this metal is

$\phi = E-K=6.5 eV-4.0 eV=2.5 eV$

So, the metal is Lithium.

B. cesium, potassium, sodium

The wavelength of green light is

$\lambda=510 nm=5.1\cdot 10^{-7} m$

So its energy is

$E=\frac{hc}{\lambda}=\frac{(6.63\cdot 10^{-34}Js)(3\cdot 10^8 m/s)}{5.1\cdot 10^{-7} m}=3.9\cdot 10^{-19}J$

Converting in electronvolts,

$E=\frac{3.9\cdot 10^{-19}J}{1.6\cdot 10^{-19} J/eV}=2.4 eV$

So, all the metals that have work function smaller than this value will be able to emit photoelectrons, so:

Cesium

Potassium

Sodium

C. 4.9 eV

In this case, we have

- Copper work function: $\phi = 4.5 eV$

- Maximum kinetic energy of the emitted electrons: K = 2.7 eV

So, the energy of the incident light is

$E=\phi+K=4.5 eV+2.7 eV=7.2 eV$

Then the copper is replaced with sodium, which has work function of

$\phi = 2.3 eV$

So, if the same light shine on sodium, then the maximum kinetic energy of the emitted electrons will be

$K=E-\phi = 7.2 eV-2.3 eV=4.9 eV$

7 0

4 years ago

Please help me! I don’t get this

goldfiish [28.3K]

The answer will be

(1) correct

(2) correct

(3) the force of the soccer ball on the net

(4) Will not change

Hope this help

4 0

3 years ago

Read 2 more answers

Which statement about thermal energy is true?

NNADVOKAT [17]

Answer:Thermal energy is a measure of a substance 's specific heat

Explanation:

7 0

3 years ago

Read 2 more answers

In a chemical reaction, one element replaces another element in a compound to form a new substance. Which of the following best

Andreyy89

Answer:

single replacement

Explanation:

In the question it says one element replaces another element which means there is only one replacement.

3 0

3 years ago

Determine the kinetic of 600 kg roller coaster car that is moving with the speed of 35.2 m/s.

antiseptic1488 [7]

The answer is 10,560 Joules or 1.1*10^4

Explanation:

Step 1: Calculate
The equation for Kinetic Energy is

Kinetic energy=.5 times Mass times Velocity²
KE=.5*m*v²

so we plug in our numbers
KE=.5*600*35.2²

This works out to be 10,560 Joules or 1.1*10^4

5 0

3 years ago