# Homework Help: Quantum Physics Problem

1. May 1, 2005

### Tokimasa

In a photoelectric experiment, light is incident on a metal surfact. Photoelectrons are ejected, producing a current. A reverse potantial is applied and adjusted until the current drops to 0 (this is called the stopping potential). This fata is collected for stopping potentials (listed first) for four different frequencies (listed second): [typo volts that reads 0,] and 2E14Hz; 0.9V and 4E14Hz; 2V and 7E14Hz; 3V and 9.3E14Hz.

Determine an experimental value for Planck's constant. What is the work function of the metal?

----------

Can someone tell me what formulas to use?

2. May 1, 2005

### Gokul43201

Staff Emeritus
3. May 1, 2005

### Tokimasa

Well, I'm given two formulas for Photoelectric Effect wiht little about them. The only one that I have no idea what it is states: KE[max] = eV[0]. I know that eV is electron Volts, but I don't think that's what the formula is saying.

4. May 2, 2005

### Gokul43201

Staff Emeritus
KE(max) : maximum kinetic energy (~0.5mv^2) of ejected photoelectron
e : charge on the electron = 1.6 * 10^-19 coulombs
V(0) : applied stopping potential in volts