Track quiz
Show on a big screenHere are the nine rules from the lessons. Then try the questions.
| Idea | The rule |
|---|---|
| Bouncing by the rule | The angle of reflection equals the angle of incidence. Both are measured from the normal. |
| Mirrors that are not flat | For a small spherical mirror, f = R/2. |
| What the mirror does to an image | The place of the object decides the image. A convex mirror makes a virtual, upright, smaller image. This is true for a real object, wherever it stands. |
| Two rays are enough | Draw any two standard rays. Where they cross, or seem to cross, is the image. |
| The mirror formula | 1/v + 1/u = 1/f, m = −v/u |
| Bending by a rule too | Entering an optically denser material, a ray bends towards the normal. Leaving it, the ray bends away. |
| The lens formula | 1/v − 1/u = 1/f, m = v/u. A concave lens makes a virtual, upright, smaller image. This is true for a real object, wherever it stands. |
| How strong a lens is | P = 1/f, with f in metres. Powers of touching lenses add. |
| Through a glass slab | A glass slab has air on both sides. A ray leaves it parallel to the ray that entered. It is shifted sideways. The shift is the lateral displacement. It is the gap between the two rays. Measure it at right angles to them. The shift is zero along the normal. It grows with thicker glass. It grows with a bigger angle of incidence. It grows with a higher refractive index. |
A ray meets a plane mirror at 30° to its surface. What is the angle of reflection?
A ray through the centre of curvature C hits a concave mirror. What is its angle of incidence?
A concave mirror has a radius of curvature of 36 cm. What is its focal length?
An object stands between C and F of a concave mirror. Where is the image?
A convex mirror forms an image of a real object. What is the image like?
A concave mirror has f = 20 cm. An object is 30 cm in front. Find v.
A ray goes from air into glass at a slant. Which way does it bend?
The refractive index of glass is 1.5. Light in a vacuum travels at 3 × 10⁸ m/s. What is its speed in glass?
A convex lens has f = 15 cm. An object is 10 cm in front. What is the image?
A lens has a focal length of −0.2 m. What is its power?
Two lenses of +6 D and −2 D touch. What is their power together?
A ray in air crosses a glass slab. Its angle of incidence is 40°. How does the leaving ray compare with the entering ray?
Read Chapter 9 in your Class 10 book. The next track is The Human Eye and the Colourful World.
Reveal every answer to finish this lesson.