## Refraction and Lenses

Refraction
Turn on your laser and shine it through air at the surface of water. Change the laser's angle and observe the effect. Swap out the water and replace it with oil or glass or diamond or ... . Switch to the other side of the boundary and observe the effect of laser light traveling from water to air. There's no end to what you can try with this Interactive ... without an expensive laser, without getting wet, and without having to buy any diamonds.

Now available with two Concept Checkers.

Least Time Principle
If you were a lifeguard at the beach and you saw a struggling swimmer in the water, it would be your objective to reach the swimmer in the least amount of time. But since you can run faster on the sand than you can swim in the water, you can't run directly at the swimmer. You can reduce your time by running a longer distance on the sand and swimming a shorter distance in the water. Your path to the swimmer will be a bent path - bent at the point where you transition from running to swimming. In this Interactive, learners will determine the entry point into the water that results in the least time. Then their analysis of the data will relate principle of least time to Snell's law of refraction. Now go save that swimmer ... in the least amount of time.

Optics Bench - Lenses
Every child has had the fascinating experience of looking through a magnifying glass. Many of us have taken the magnifying glass and looked at far away objects only to notice that the magnifying effect no longer occurs. So what exactly is going on with the lens of a magnifying glass? In this Interactive, learners will explore a converging lens. A candle can be dragged to varying locations and the characteristics of the image can be quickly observed. There is an activity sheet to accompany this Interactive.

Now available with a Concept Checker.

The Physics Classroom thank their friends at Nerd Island Studios for contributing this Interactive to our collection.

Converging Lens Image Formation
"An image is formed by a lens when light from every point on the object intersects at a location in space." That's nice theory, but it's a little difficult to get a mental grip on. But now that has changed with our Converging Lens Image Formation simulation. Tap the link and watch as our Interactive constructs the image of every point on an object using a rapidly-draw ray diagram. The process and the result will fascinate you. Tap the link and secure your grip on image formation.

Diverging Lens Image Formation
Find out how a diverging lens forms an image. Tap on a point on an object and view the light refracting and being traced backwards to an intersection point. Repeat for a variety of object locations and learn about image formation for diverging lenses.