The apparatus shown is used to investigate photoemission - Scottish Highers Physics - Question 9 - 2022

To find metal X, we first calculate the work function $E$ using the previously determined threshold frequency:

$E = hf_0$

Where:

• $h$ (Planck's constant) = $6.63 imes 10^{-34} ext{ J s}$

Substituting the threshold frequency:

$E = 6.63 imes 10^{-34} imes 7.0 imes 10^{14} = 4.64 imes 10^{-19} ext{ J}$

Comparing this value with the work function of the metals:

• Potassium: $3.7 imes 10^{-19} ext{ J}$
• Calcium: $4.6 imes 10^{-19} ext{ J}$
• Zinc: $4.3 imes 10^{-19} ext{ J}$
• Gold: $8.5 imes 10^{-19} ext{ J}$

The work function of calcium is the closest to our calculated value. Therefore, metal X is:

Calcium