Track quiz
Before the questions, here are the eight rules this track worked with.
| Idea | The rule, as the lab applies it |
|---|---|
| The law of reflection | The angle of incidence equals the angle of reflection. Both are measured from the normal. The normal is at 90° to the mirror. |
| Behind the glass | The image stands as far behind as the object stands in front. It is the same size and upright. Left and right are swapped. |
| Two more kinds of mirror | A plane mirror gives an upright image of the same size. A convex mirror gives an upright, smaller image. A concave mirror gives an upright, larger image when close. Further away, the image is upside down. First it is still larger, then it gets smaller. |
| Curved mirrors | Parallel rays stay parallel after a plane mirror. A concave mirror brings them together. A convex mirror spreads them apart. |
| Light bends | Light bends where it goes from air into water. It bends toward the normal. A ray along the normal does not bend. |
| The pencil that looks bent | Light bends again where it leaves water. So a thing under water looks higher than it is. The thing has not moved. |
| Lenses | A lens thicker in the middle (convex) makes parallel rays meet. A lens thinner in the middle (concave) makes them spread. A flat glass sheet does not make them meet or spread. |
| What a lens shows | A convex lens close to an object gives an upright, larger image. Further away, the image is upside down. First it is still larger, then it gets smaller. A concave lens always gives an upright, smaller image. |
A ray hits a mirror. The angle of incidence is 35°. What is the angle of reflection?
The angle of incidence is 35°. What angle does the reflected ray make with the mirror?
You stand 2 m in front of a plane mirror. How far behind it is your image?
An image is upright and smaller than the object. Which mirror made it?
A concave mirror shows your face upside down from far away. What must you do to see it upright?
Parallel rays hit a concave mirror. What do the reflected rays do?
Why is a convex mirror used as a side-view mirror?
A pencil in a glass of water looks bent. Why?
Parallel rays fall on a lens that is thicker in the middle. What happens?
Which lens always gives an upright, smaller image?
Now open your NCERT book. Meet the same ideas in its questions.
Next is Keeping Time with the Skies. It asks where the calendar came from.