Calculate the threshold energy in kj/mol of electrons in aluminum, given that the lowest frequency photon for which the photoelectric effect is observed is 9.87 × 1014 hz.

The threshold energy of the electrons in aluminium is 393.71 kJ/mol.

Explanation: Threshold energy is the minimum amount of energy which is required to emit a photon from a metal surface.

Mathematically,

Where,

E = Threshold energy

= Avogadro's constant =

h = Planck's Constant =

= Frequency of the particle =

Putting values in above equation, we get:

  (Conversion Factor: 1kJ = 1000J)

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27