EMS Waves Review

What type of wave are EM waves

Electromagnetic waves are transverse waves that do not require a medium to travel

The electromagnetic spectrum organizes waves in order of increasing

frequency and energy, and decreasing wavelength

When light moves from air to glass, the speed of light

decreases because glass is more optically dense than air

A material that reflects or absorbs all light that hits it is known as

opaque

A material that allows some light through while scattering the rest that strikes it is called

translucent

A material that allows some light through while scattering the rest that strikes it is called

translucent

What is the law of reflection? Explain how it occurs

The law of reflection states that the angle of incidence is equal to the angle of reflection. It occurs when light bounces off a surface in a predictable way, with both angles measured from the normal line

What is a diffuse reflection? Why does it occur

Diffuse reflection is when light reflects in many different directions. It occurs because the surface is rough or uneven, causing incoming light rays to scatter

Know the electromagnetic spectrum (all 7 types of EM waves) and the order that they go in

Radio waves → Microwaves → Infrared → Visible light → Ultraviolet → X-rays → Gamma rays

Describe what happens to white light when it passes through a glass prism and explain why it occurs

White light separates into a spectrum of colors (rainbow) because different wavelengths of light bend by different amounts when entering and exiting the prism, a process called dispersion

Identify a convex vs. concave lens and explain why its shape allows the lens to be used in this way

A convex lens is thicker in the middle and converges (focuses) light rays to a point, making it useful for magnifying or focusing images. A concave lens is thinner in the middle and diverges light rays, spreading them out and making objects appear smaller

What is the difference between the visible colors of light with regards to energy, wavelength, and frequency

Colors differ by wavelength, frequency, and energy. Red light has the longest wavelength, lowest frequency, and lowest energy, while violet light has the shortest wavelength, highest frequency, and highest energy

Electromagnetic spectrum order

increasing frequency and energy

Wavelength trend

decreases across the spectrum

Light from air to glass

slows down

Opaque

no light passes through

Translucent

some light passes, scattered

Law of reflection

angle in = angle out

Normal line

perpendicular to surface

Diffuse reflection

light scatters in many directions

Cause of diffuse reflection

rough surface

EM spectrum order

radio → micro → infrared → visible → UV → X-ray → gamma

White light in prism

splits into colors

Reason for prism effect

dispersion (different bending)

Convex lens

converges light (focuses)

Concave lens

diverges light (spreads out)

Red light

long wavelength, low energy

Violet light

short wavelength, high energy

Frequency vs energy

higher frequency = higher energy

Radio Waves

Longest wavelength, lowest energy

Microwaves

Used for cooking & communication

Infrared

Heat waves

Visible Light

ROYGBIV (what humans can see)

Red

Longest wavelength in visible light

Orange

Between red and yellow

Yellow

Middle of visible spectrum

Green

Middle visible color

Blue

Shorter wavelength, higher energy

Indigo

Between blue and violet

Purple (Violet)

Shortest wavelength in visible light

UV Rays

Higher energy than visible light (can cause sunburn)

X-rays

Very high energy, used in medical imaging

Gamma Rays

Highest energy, shortest wavelength

Transparent

Light passes through clearly

Translucent

Some light passes, but blurry

Opaque

No light passes through

Law of Reflection

Angle of incidence = angle of reflection

Diffuse Reflection

Light scatters on rough surfaces

Specular (Regular) Reflection

Light reflects evenly on smooth surfaces

Convex Mirror

Makes images appear smaller

Concave Lens (Diverging)

Spreads light out

Converging Lens

Focuses light to a point

Dispersion

Separation of light into colors (like a prism)

Photon

Particle of light

Energy of Light

Depends on frequency (higher frequency = higher energy)

Electromagnetic Waves

Do NOT need a medium to travel

Reflection

Light bounces off a surface

Refraction

Light bends when changing mediums

Cause of Refraction

Change in speed of light

Reflection Example

Mirror

Refraction Example

Straw looks bent in water

White Light

Contains all colors

Object Color

Determined by what light is reflected

Purple Object

Reflects purple wavelengths, absorbs others

📊 Refraction Graph & Trends

Angle of Incidence vs Refraction

As incidence increases → refraction increases

Key Pattern

Refraction angle is ALWAYS smaller than incidence (in air → water)

Prediction Rule

If incidence increases → refraction increases but stays lower

70° Prediction

Refraction will increase (around mid-40s°), still less than 70°