1. Define circular motion and oscillatory motion with one example? 2. Handspan and cubit cannot used as a standard units of lengths? 3. Define reflection of light and lateral inversion? 4. Write down two laws of reflection ? 5. Define Pinhole camera ,?Write down two advantages of pinhole camera? 6. Define term diffused and irregular reflection? And how virtual image formed? .
Answers
1 the motion of a pendulum is both oscillatory motion and periodic motion but the motion of the wheels of a car is only periodic because the wheels rotate in a circular motion. Circular motion is only periodic motion and not oscillatory motion. The wheels do not move to and fro about a mean position.
2 Handspan and cubit cannot be used as a standard unit of length . This is because these are not particular measurements . Like the handspan will vary from person to person and the true value would not be same . This is the biggest limitation .
3 Reflection Of Light In A Mirror: Lateral Inversion/Left-Right Reversal. ... Reflection of light is referred to the change in the direction of light upon striking a surface. This change in direction occurs whenever light hits a surface, irrespective of the texture or the nature of the surface.
4 The two laws of reflection are as follows: The incident ray, the reflected ray and the normal all lie in the same plane. The angle of incidence is equal to angle of reflection.
5 The main advantage is the same as the main disadvantage: Its simplicity. The "lens" of a pinhole camera is the size of the whole. You can only use a very small hole.
Very long exposure times.
Soft focus.
Limited subject matter due to simplicity of the camera and the long exposures required.
6 Regular and Irregular Reflection - definition
parallel rays remain parallel after reflection. Irregular Reflection: 1. Reflection from a rough surface is called diffuse reflection.