Atomic and Nuclear Physics 1

Basic Nuclear PhysicsUse Pages 365-371 to Answer These

Questions

1. Who discovered radioactivity? How?

2. What do the Z and A mean?3. How many of each atomic particle

are there in potassium?

4. What is an isotope?5. Why is mass not directly

proportional to charge in the nucleus?

6. What is an ion?7. Explain Rutherford's gold leaf

experiment and its implications.

8. Why do the paths of particles curve by different amounts in a B field?

9. Name and describe 3 types of radio active emissions

A

Z

X

39

19

K

Atomic and Nuclear Physics 2

Basic Nuclear Physics

Use Pages 365-371 to Answer These Questions

10 What are the relative ionizing and penetrating abilities of the 3 nuclear emissions?

11 How is radioactivity measured?12 What is half-life?13 What is conserved in a nuclear reaction?14 Complete: 226

88Ra 22286Rn

15 Do you have a radioactive source in your home?

Now try problems 1-8 on page 385 in your text.

Atomic and Nuclear Physics 3

The Photoelectric Effect

Ref: page 332-338

This occurs when light shines onto a piece of shiny metal and causes electrons to be given off.

U.V. light is needed for most metals. Uses: ???

What happens when?

The frequency of light is changed

The brightness of light is changed

Atomic and Nuclear Physics 4

The Photoelectric Effect

Ref: page 332-338

Photons

Packets or quanta of energy.

Fixed amount of energy

E f E=hf

h=plancks constant 6.63x10-

34JsInvestigating the Photoelectric Effect

Adjust the voltage so electrons are just stopped and the current is zero.

The voltage is noted for different frequencies of light.

Atomic and Nuclear Physics 5

Investigating the Photoelectric Effect

Ref:P336

V

ffo

V vs. ffo is the threshold frequency, below this value no electrons are given off.

kinetic energy=voltage x charge

Ek=Ve= max Ek of emitted electrons

The graph can therefore be drawn as:

Ek

ffo

Ek vs. f

The gradient of the graph is h Planck's constant

is the work function or minimum amount of energy required for electrons to escape the surface.

Ek = hf -

Atomic and Nuclear Physics 6

Photoelectric Effect Problems

1) Which formula on your formula sheet refers to the photo electric effect.

2) What does hf , Ek and refer to?

3) What two things would be different about the graph of Ek vs. f if a different metal were used?

4) What would be the same on the above graph if a different metal were used?

Try text problems 1-11 page 347-348.