Leaving Cert Physics The Electron: The work function of tungsten is

The work function of tungsten is 4.50 eV - Leaving Cert Physics - Question (h) - 2014

Question (h)

The work function of tungsten is 4.50 eV. Calculate the maximum kinetic energy of an electron ejected from a tungsten surface when electromagnetic radiation whose ph... show full transcript

Worked Solution & Example Answer:The work function of tungsten is 4.50 eV - Leaving Cert Physics - Question (h) - 2014

Step 1

Calculate the Energy of Incident Photon

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Answer

The energy of the incident photon can be expressed as the sum of the work function and the kinetic energy (KE) of the ejected electron. The formula used is:

$E_{photon} = Work \, function + KE_{electron}$

Given:

Photon energy ( $E_{photon}$ ) = 5.85 eV
Work function ( $ext{Work function}$ ) = 4.50 eV

Now, substituting the known values, we have:

$5.85 \, eV = 4.50 \, eV + KE_{electron}$

Step 2

Rearrange to Find the Kinetic Energy

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Answer

Rearranging the equation to solve for the kinetic energy:

$KE_{electron} = E_{photon} - Work \, function$ Substituting the values:

$KE_{electron} = 5.85 \, eV - 4.50 \, eV$ $KE_{electron} = 1.35 \, eV$

Step 3

Convert Kinetic Energy to Joules (if required)

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Answer

To convert the kinetic energy from electronvolts to joules, we use the conversion factor:

$1 \, eV = 1.6 imes 10^{-19} \, J$

Thus, the kinetic energy in joules is:

$KE_{electron} = 1.35 \, eV \times 1.6 imes 10^{-19} \, J/eV = 2.16 \times 10^{-19} \, J$

Step 4

Final Result

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Answer

The maximum kinetic energy of the electron ejected from the tungsten surface is therefore:

1.35 eV (or 2.16 x 10^-19 J) after conversion.

The work function of tungsten is 4.50 eV - Leaving Cert Physics - Question (h) - 2014

Worked Solution & Example Answer:The work function of tungsten is 4.50 eV - Leaving Cert Physics - Question (h) - 2014

Calculate the Energy of Incident Photon

Rearrange to Find the Kinetic Energy

Convert Kinetic Energy to Joules (if required)

Final Result

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