5.1 – Light and Quantized Energy – Part 1

• OBJECTIVES: Students will be able to (SWBAT)

1. Predict the changes in wavelength and frequency based

on direct or indirect relationships

2. Describe the different forms of electromagnetic

radiation of the electromagnetic spectrum in terms of

2. Describe the different forms of electromagnetic

radiation of the electromagnetic spectrum in terms of

wavelength and frequency

• 8 lecture/10 reading questions

• 5-sentence summary

Notes: 5.1 – Light and Quantized

Energy – Part 1

Nuclear Atomic Model was Incomplete

• Rutherford’s model does not answer:

– why different elements have such different physical and

chemical properties

– how electrons behave and are arranged in an atom

• So scientists looked at the types of visible light • So scientists looked at the types of visible light

emitted from different elements and chemicals

– Helped them to understand the behavior of electrons

and their arrangement in atoms

Light travels in waves

• All energy travels in waves

• Energy in wave form � electromagnetic

radiation

Characteristics of a Wave

• WAVELENGTH (λ – Greek symbol lambda) – distance

from top to top (or bottom to bottom) of a wave

(units is meters (m) or nanometers (nm)wavelength

Highest part

of wave

Length of wave from crest to crest (or trough to

trough)

Amplitude

Height of wave

Lowest part

of wave

Converting from nm � m

• Attach “×10-9 m” to any value that is in nm

• Don’t worry about proper scientific notation form

• For example,• For example,

– 8.9 nm � m

– 24.3 nm � m

– 571 nm �m

8.9×10-9 m

24.3×10-9 m

571×10-9 m

Characteristics of a Wave

• FREQUENCY (ν – Greek symbol nu) – how frequently

the waves passes a fixed point

– Units is 1 cycle per second or 1

s

– All units of frequency:

= s-1 = hertz (Hz)

– Megahertz (MHz) is used also

s

1

s

Converting from MHz � Hz

• Attach “×106 Hz” to any value that is in MHz

• For example,

– 7.8 MHz � Hz 7.8×106 Hz– 7.8 MHz � Hz

– 90.4 MHz � Hz

– 162 MHz �Hz

7.8×106 Hz

90.4×106 Hz

162×106 Hz

Inverse or indirect Relationship

• Indirect or inverse proportional relationship

– As one value goes up, the other value goes down

(and vice versa)

• Wavelength and frequency have an indirect • Wavelength and frequency have an indirect

proportional relationship

– Wavelength ↑, frequency ↓ (λ ↑, ν ↓)

– Wavelength ↓, frequency ↑ (λ ↓, ν ↑)

Proportional Relationships

• Direct or directly proportional

– X ↑, Y ↑ (and X ↓, Y ↓)

• Inverse or indirectly proportional

– X ↑, Y ↓ (and X ↓, Y ↑)

• Wavelength and frequency have an indirectly • Wavelength and frequency have an indirectly

proportional relationship

– λ ↑, ν ↓

– λ ↓, ν ↑

Longest wavelength,

lowest frequency

↓

shortest wavelength,

highest frequency

↓

Electromagnetic Spectrum

• Electromagnetic spectrum (EMS) contains all types

of electromagnetic radiation

Radio Waves

• Longest wavelengths, lowest frequencies

• Radio, television and cell phone signals are sent

through radio waves

• Due to their very long wavelengths, often interfere

with other EMR’s (usually asked to shut off with other EMR’s (usually asked to shut off

equipment when other EMR’s are used…like in

planes and doctor’s office)

Microwaves

• Higher frequencies (than radio waves) allow uses

for cooking, radar, telecommunications and cell

phones

Infrared Waves

• Infrared waves are given off from a heat source and

allows for thermal imaging (heat-vision or night-

vision goggles)

• Some animals, like snakes, can sense infrared waves

Visible Light Waves

• Visible light waves come from light sources that

humans and other animals can detect

• Allows us to see various colors

• White light is a combination of all colors of the

visibile light spectrumvisibile light spectrum

Colors of Visible Light

Ultraviolet Waves

• The Sun, along with other types of EMR, emits

ultraviolet, or UV, waves

• Are harmful to humans in that they cannot be

blocked by human skin

• Can cause sunburns and skin cancer• Can cause sunburns and skin cancer

X-Rays

• Powerful x-rays can penetrate many surfaces such

as human skin to take photos of bones and

skeletons

• Also used in security measures such as at the

airportairport

Gamma Rays

• Most powerful waves of the EMS (highest

frequency, smallest wavelength)

• Result of many nuclear reactions and cosmic

(stellar) explosions

White Light

• White light is composed of a continuous spectrum

of colors from the visible spectrum within the EMS

– R.O.Y.G.B.I.V.: red, orange, yellow, green, blue, indigo,

violet

• Can be separated by bending, or refracting• Can be separated by bending, or refracting

What type(s) of electromagnetic

radiation do we get from the Sun?

What type(s) of electromagnetic

radiation do we get from the Sun?