The photoelectric work function of a metal is the minimum energy needed to eject an electron by irradiating the metal with light. For calcium, this work function equals 4.34 x 10-19 J. If light with a wavelength of 256 nm impinges on a piece of calcium, what is the speed of the ejected electron in m/s?

I was able to find the kinetic energy of the electron as 3.4x10^-19J but I can't figure out how to convert that to m/s

See your post above.

To find the speed of the ejected electron, you can use the kinetic energy formula:

Kinetic energy (KE) = (1/2) * mass * velocity^2

First, you need to find the mass of the electron. The mass of an electron is approximately 9.11 x 10^-31 kg.

Since you already found the value for the kinetic energy (KE) as 3.4 x 10^-19 J, you can set up the equation:

3.4 x 10^-19 J = (1/2) * 9.11 x 10^-31 kg * velocity^2

Now, rearrange the equation to solve for the velocity:

velocity^2 = (2 * 3.4 x 10^-19 J) / (9.11 x 10^-31 kg)

Simplifying the equation further:

velocity^2 = 0.374 / 9.11 x 10^-12

velocity^2 = 4.107 x 10^11

Finally, take the square root of both sides to find the velocity:

velocity = √(4.107 x 10^11)

velocity ≈ 2.026 x 10^5 m/s

Therefore, the speed of the ejected electron is approximately 2.026 x 10^5 m/s.

To find the speed of the ejected electron, we can use the kinetic energy (KE) of the electron. The equation that relates kinetic energy to the speed of an object is:

KE = (1/2)mv^2

Where m is the mass of the object and v is its velocity (speed). In this case, we don't have the mass of the electron directly given, but we can use the fact that electrons are very light particles and their mass is approximately 9.11 x 10^-31 kg.

Let's substitute the values we have into the equation:

KE = 3.4 x 10^-19 J
m = 9.11 x 10^-31 kg

Rearranging the equation to solve for v:

v^2 = 2KE / m
v = √(2KE / m)

Plugging in the values:

v = √(2 x 3.4 x 10^-19 J / (9.11 x 10^-31 kg))

Calculating the expression inside the square root:

v = √(6.8 x 10^-19 J / (9.11 x 10^-31 kg))

Now, let's evaluate this expression:

v ≈ √746 x 10^12 m^2/s^2

Finally, let's calculate the square root:

v ≈ 8.63 x 10^6 m/s

Therefore, the speed of the ejected electron is approximately 8.63 x 10^6 m/s.