light

• Source of light:

  • Any object which emits light is called a source of light
  • The sun is a natural source of light
• Non-luminous objects:

  • Reflect the light falling on them
  • The reflected light is sensed by the eye, allowing us to see non-luminous objects
• Shadows:

  • A dark space or region where an opaque object blocks the light rays is known as a shadow
• Solar Eclipse:

  • Occurs when the moon is between the earth and the sun in a straight line
  • Moon blocks the sunlight, causing a shadow on the earth
• Lunar Eclipse:

  • Occurs when the earth is between the sun and the moon in a straight line
  • Earth blocks the sunlight, causing the moon to be in shadow
• Total solar eclipse:

  • Can be seen in the part of the Earth where the Sun is completely blocked by the Moon
• Image formed by a pinhole camera:

  • Real, inverted, and diminished
• Principle of a pinhole camera:

  • Based on the principle of rectilinear light motion, where light travels in straight lines
• Effect of distance on image size in a pinhole camera:

  • As the distance between the object and the pinhole decreases, the image size increases
  • If the distance is increased, the image becomes smaller
• Reflection in a plane mirror:

  • Light falling on a plane mirror is reflected, changing its direction
• Parallel beam of light:

  • Rays are parallel to each other with a constant distance between them
• Convergent beam of light:

  • Rays meet or converge at a point, with the distance between them decreasing
• Divergent beam of light:

  • Rays spread out from a point, with the distance between them increasing
• Differences between luminous and non-luminous objects:

  • Luminous objects emit their own light (e.g., Sun, stars)
  • Non-luminous objects reflect light (e.g., Moon, pencil)
• Experiment to demonstrate rectilinear propagation of light:

  • Use three cardboard pieces with holes in a straight line
  • Light a candle behind the first cardboard and observe the flame through the holes
  • Moving any cardboard will disrupt the straight line of light, showing light travels straight
• Differences between image formed by a plane mirror and a shadow:

  • Image shows the same color as the object, while a shadow is always a dark region
  • Image shows all details of the object, while shadows show only the outline and shape
  • Image size is always the same as the object, while shadow size depends on the light source position
  • Image formation by a plane mirror is due to reflection, while a shadow is formed by light obstruction