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## Refraction

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**When a car drives through a puddle,**it will slow down because Of drag on the wheels caused by the water Refraction If the puddle is at right angles to the car, it will continue to travel straight**If the puddle is at an angle, as shown here, one wheel will**slow down first, causing the car to turn. When the other wheel hits the water, it too will slow. The wheels will leave the puddle at different times causing one to speed up first, and the car will straighten up Refraction If the puddle is at right angles to the car, it will continue to travel straight**The greater the angle , the more time before both wheels are**in the water So the greater the angle of bending The deeper the water, the more the first wheel will slow down So the greater the angle of bending Refraction**Refraction**The waves of light will behave the same way The more optically dense the medium, the greater the bending of the light**Refraction**• Refraction is caused by light changing speed • The ratio of speed of light in a vacuum to the speed of light in a medium is known as the refractive index • = • Every transparent substance will have its own refractive index**Refraction**= 1.50 1. The speed of light in a vacuum is 3.0 x 108ms-1and in chloroform its speed is 2.0 x 108ms-1 . Calculate the refractive index value, n, for chloroform. =**Refraction**• In which transparent substance does light travel the slowest? • The higher the refractive index, the slower light travels - diamond • In which 'substance' does light travel the fastest? • The lower the refractive index, the faster light travels - water**Refraction**Calculate the speed of light in glass = 1.50 So = = 2.0 x 108 ms-1**Refraction**Calculate the speed of light in water = 1.33 So = = 2.26 x 108 ms-1**Refraction**Calculate the speed of light in diamond = 2.41 So = = 1.24 x 108 ms-1