SP5 - Light and the Electromagnetic Spectrum ✓

• Reflection • Refraction

• i: Angle of incidence (between incident ray and the normal) • r: Angle of reflection/refraction (between reflected/refracted ray and the normal)

i = r (Angle of incidence = angle of reflection/refraction) This is the law of reflection

The line drawn perpendicular to the object light is reflecting off (or refracting through)

• TIR occurs when light refracts through a substance at sucha low angle of incidence that it doesn’t leave the other side • This angle is called the critical • If light enters at the critical, it will move along the interface • If light enters at an angle smaller than the critical, it will cause TIR to happen

• Place a ray box with a slit in front of it on a piece of paper • Place a glass box the way of the ray of light thta is being produced • Draw around the glass block • Mark the point of entry and exit for the light aswell as two further points (such as origin and edge of paper) on the piece of paper • Use your markings to draw lines representing the travel of the ray of light • Repeat with ray box at different angles and compare your results

• Specular: When light is reflected evenly on a smooth surface • Diffuse: When light is reflected in all directions on a rough surface

• Sunlight is made up of white light as it contains all the colours of the visible spectrum • An object that appears green will reflect the green part of the spectrum but reflect all the other colours

A blue filter would only transmit the blue part of the light that goes to it.

• They are all transverse waves • They all travel at (3x10^8m/s) ina vacuum • They transfer energy

• A prism was used to refract white light into the seven componenets. • A thermometer was placed just outside of the red part of this spectrum. • Another was placed in the spectrum. • The thermometer next to red was warmer suggesting there was something warming it up

ROYGBIV • Red • Orange • Yellow • Green • Blue • Indigo • Violet

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

EM waves of different length get absorbed by different amounts by the atmosphere

• Heating food • Short range communication such as TV remotes • Security systems

• Communications and satellite transmissions • Heating up food and giving it energy

• Transmitting radio broadcasts • Radio communications via satellites

• Oscillations in electrical signals. • Metal rods can be used as aerials because they can absorb and transmit these oscillations

• The way radio waves and microwaves travel is dependant on the angles they reach the ionosphere. • At all angles, microwaves pass straight through and so there is maximum range they can be fired in a straight line. • At some angles, radio waves are reflected by the ionosphere, becasue they have larger wavelengths. • This means they don’t have to be fired directly to a point

• Disinfect waters by killing microorganisms • Invisible ink due to fluoresence • Security on bank notes

Imaging of the inside of the body

• Radiotherapy • Sterilisation of medical equipment and food • PET scanner

• Infrared radiation is absorbed by our body. • We feel it as heat and an excess of it can destroy cells burning skin

It can cause sunburn and damage to DNA which can lead to skin cancer