F O R M 1 N O T E S:R E C T I L I N E A R P R O P A G A T I O N O F L I G H T Pg 716. A building standing 100m from a pinhole camera produces on the screen of thecamera an image 5 cm high 10 cm behind the pinhole. Determine the actualheight of the building. (3mk)17. A pinhole camera forms an image of size 10cm. The object is 5m tall and20m away from the pinhole. Find the length of the pinhole camera. (3mk)18. The figure below shows an object placed infront of a pinhole camera. Usingrays, show how the image is formed on the screen. (3mk)SHADOWS19. What are the conditions necessary for the occurrence of annular eclipse?.(2mk)20. State two factors affecting the type of shadow formed by an object placedinfront of a source of light. (2mks)21. Describe how a solar eclipse occurs using a well labeled diagram (3mks)22. Light from a point source falls on an object. Draw rays to show how the shadowof the object is formed on the screen and name the shadows. (3mk)23. The figure shows three point sources of light with an opaque object placedbetween them and the screen.ObjectPinhole ScreenOpaque objectLightSourceScreenOpaque objectLightSourceScreenCBADF O R M 1 N O T E S:R E C T I L I N E A R P R O P A G A T I O N O F L I G H T Pg 8State and explain the nature of shadow formed along BC. (2mks)24. When the moon comes between the sun and the earth in a straight line, aneclipse occurs. Name the eclipse. (1 mk)25. Draw a ray diagram to show the formation of a partially dark shadow and atotally dark shadow during the eclipse of the sun. (3mk)

1. To determine the actual height of the building, we can use similar triangles.

Given that the image on the screen is 5 cm high and the distance behind the pinhole is 10 cm, we can set up the following proportion:

(actual height of the building) / (distance of the building from the pinhole) = (height of the image on the screen) / (distance behind the pinhole)

Let's substitute the given values into the proportion:

(actual height of the building) / 100m = 5cm / 10cm

Simplifying the proportion:

(actual height of the building) / 100 = 0.5

Cross-multiplying:

(actual height of the building) = 100 * 0.5

(actual height of the building) = 50m

Therefore, the actual height of the building is 50 meters.

2. To find the length of the pinhole camera, we can use similar triangles again.

Given that the image size is 10 cm, the object height is 5m, and the object distance from the pinhole is 20m, we can set up the following proportion:

(length of the pinhole camera) / (object distance from the pinhole) = (image size) / (object height)

Let's substitute the given values into the proportion:

(length of the pinhole camera) / 20m = 10cm / 5m

Simplifying the proportion:

(length of the pinhole camera) / 20 = 2

Cross-multiplying:

(length of the pinhole camera) = 20 * 2

(length of the pinhole camera) = 40m

Therefore, the length of the pinhole camera is 40 meters.

3. To show how the image is formed on the screen in a pinhole camera, we can use rays.

First, draw an object in front of the pinhole camera. Then, draw three rays from the top of the object, passing through the pinhole, and reaching the screen. These rays should be parallel to each other.

The first ray should pass through the top of the object and go straight through the pinhole to the screen. This ray represents the top of the object.

The second ray should pass through the bottom of the object and go straight through the pinhole to the screen. This ray represents the bottom of the object.

The third ray should pass through the middle of the object and go straight through the pinhole to the screen. This ray represents the middle of the object.

Where these rays intersect on the screen, an inverted image of the object will be formed.

4. The conditions necessary for the occurrence of an annular eclipse are:

• The moon must be in its new moon phase, which means it is directly between the Earth and the Sun.
• The moon must be at or near its apogee, which is the farthest point in its orbit from the Earth.
• The Earth must be in alignment with the Sun and the moon, forming a straight line.

5. Two factors affecting the type of shadow formed by an object placed in front of a source of light are:

• The size of the object: A larger object will cast a larger shadow, while a smaller object will cast a smaller shadow.
• The distance between the object and the light source: If the object is closer to the light source, the shadow will be larger and more defined. If the object is farther away, the shadow will be smaller and less defined.

6. A solar eclipse occurs when the moon comes between the sun and the Earth in a straight line. Here is a description of how it occurs:

• The moon is in its new moon phase, which means it is directly between the Earth and the Sun.
• As the moon moves in its orbit, it casts a shadow on the Earth's surface.
• If the moon's shadow falls on a certain area of the Earth, people in that area will experience a total solar eclipse, where the moon completely blocks the sun.
• If the moon's shadow falls on a larger area of the Earth, people in that area will experience a partial solar eclipse, where only a portion of the sun is blocked by the moon.

7. When light from a point source falls on an object, the shadow of the object is formed on the screen. To draw the rays and name the shadows, follow these steps:

• Draw a straight line from the point source of light to the object.
• From the top of the object, draw a ray that goes straight to the screen. This ray represents the top shadow.
• From the bottom of the object, draw a ray that goes straight to the screen. This ray represents the bottom shadow.
• Where these rays intersect on the screen, the shadows of the object will be formed. Label them as the top shadow and the bottom shadow.

8. Along BC, the nature of the shadow formed is a partially dark shadow. This is because BC is partially illuminated by the light sources on either side, but it is also partially blocked by the opaque object in the middle.

9. When the moon comes between the sun and the Earth in a straight line, an eclipse occurs. This type of eclipse is called a solar eclipse.

10. To show the formation of a partially dark shadow and a totally dark shadow during the eclipse of the sun, draw the following ray diagram:

• Draw the sun, the moon, and the Earth in a straight line.
• From the sun, draw rays that go towards the Earth.
• From the moon, draw rays that go towards the Earth.
• Where the rays from the sun and the moon intersect on the Earth, a partially dark shadow is formed. This is the region where only a portion of the sun is blocked by the moon.
• In the region where the moon completely blocks the sun, a totally dark shadow is formed. This is the region of totality, where the sun is completely obscured by the moon.