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Grade 12th passMechanics

a conduction electron in copper near the absolute zero of temperature has kenetic energy of 4.2 ev ; what is the sped of electron?

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9 Years agoGrade 12th pass
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1 Answer

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ApprovedApproved Tutor Answer1 Year ago

To find the speed of a conduction electron in copper with a kinetic energy of 4.2 eV, we can use the relationship between kinetic energy and speed. The kinetic energy (KE) of an electron can be expressed using the formula:

Kinetic Energy Formula

The kinetic energy of an electron is given by the equation:

KE = (1/2)mv²

Where:

  • KE is the kinetic energy in joules (J)
  • m is the mass of the electron (approximately 9.11 x 10-31 kg)
  • v is the speed of the electron in meters per second (m/s)

Conversion of Energy Units

Since the kinetic energy is given in electronvolts (eV), we need to convert it to joules. The conversion factor is:

1 eV = 1.602 x 10-19 J

Thus, to convert 4.2 eV to joules:

KE = 4.2 eV × 1.602 x 10-19 J/eV = 6.72 x 10-19 J

Calculating the Speed

Now that we have the kinetic energy in joules, we can rearrange the kinetic energy formula to solve for speed:

v = sqrt((2 * KE) / m)

Substituting the values we have:

  • KE = 6.72 x 10-19 J
  • m = 9.11 x 10-31 kg

Plugging these into the equation:

v = sqrt((2 * 6.72 x 10-19 J) / (9.11 x 10-31 kg))

Calculating the numerator:

2 * 6.72 x 10-19 J = 1.344 x 10-18 J

Now, dividing by the mass:

1.344 x 10-18 J / 9.11 x 10-31 kg ≈ 1.477 x 1012 m²/s²

Finally, taking the square root gives us the speed:

v ≈ sqrt(1.477 x 1012) ≈ 1.216 x 106 m/s

Final Result

Therefore, the speed of the conduction electron in copper at near absolute zero with a kinetic energy of 4.2 eV is approximately 1.22 x 106 m/s.