## Energy Problem

$E=hv$

405289292
Posts: 52
Joined: Thu Oct 03, 2019 12:16 am

### Energy Problem

Does anyone know how to solve this problem: Molybdenum metal must absorb radiation with a minimum frequency of 1.09 x 1015 s-1 before it can emit an electron from its surface. What is the minimum energy needed to produce this effect?

Rebecca Remple 1C
Posts: 137
Joined: Wed Sep 18, 2019 12:16 am
Been upvoted: 1 time

### Re: Energy Problem

Hi there,

I solved the problem by plugging the minimum frequency into the equation E (energy) = h (Planck's constant, 6.626 * 10^-34) x v (wavelength). When I multiplied Planck's constant by the minimum frequency I got 7.22 x 10-19 J, which is the correct answer! I hope this helps :)

-Rebecca

Kayli Choy 2F
Posts: 100
Joined: Sat Aug 24, 2019 12:17 am

### Re: Energy Problem

To add on, you would use the equation E=hv because this equation calculates the energy of a photon. In order for an electron to be ejected, the incoming photon's energy must be equal to or greater than the energy needed to remove the electron (work function). Therefore, finding the minimum energy of the incoming photon would be finding the minimum energy needed to eject the electron.

Junxi Feng 3B
Posts: 52
Joined: Sat Sep 14, 2019 12:17 am

### Re: Energy Problem

To eject an electron from the surface of a metal, the incoming photo must have enough energy. Given the frequency, we can use the Einstein Equation E=hv to solve for energy E. Plug the frequency and the constant h, the resulting value will be the minimum energy required.

aishwarya_atmakuri
Posts: 101
Joined: Sat Jul 20, 2019 12:15 am

### Re: Energy Problem

Use the formula E=hv. We know that h is planck's constant (6.626*10^-34 m^2kg/s) and that v is frequency (1.09 x 10^15 s-1). If we plug these into the equation, we get E = (6.626*10^-34) (1.09 x 10^15) = 7.22 x 10^-19 J. Using the minimum frequency will also give the minimum amount of energy.