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Transparent: 1 Mark
Translucent: 1 Mark
Transparent object and a few translucent objects do notcast shadows because light passes through them.

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Each Difference: 1 Mark
$\begin{array}{cc}\text{Umbra}& \text{Penumbra}\\ \text{(1) It is the darkest region of the shadow}& \text{It is the partially shaded region which is}\text{less darker than umbra}\\ \text{(2) No light approaches this region}& \text{Some light rays reach this region}\\ \text{(3) It can be found at the centre}\text{of the shadow}& \text{It can be found in the outermost}\text{region of the shadow}\end{array}$

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Non-luminous: 1 Mark
Examples: 1 Mark
The objects, which do not emit their own light, are known as non-luminous objects. We cansee a non-luminous object only if they reflect light coming from aluminous object. Moon and earth are the examples of anon-luminous object.

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Infinite number of images will be formed in this case an image formed on one mirror will produce another image on the second mirror and so it will go on.

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Circular Shadow: 1.5 Marks
Rectangular Shadow: 1.5 Marks
A cylindrical object can cast shadows in two ways. When the top circular view faces the sun, a circular shape is formed. When it's horizontal side faces the sun, it casts a rectangular shadow.
It will look like the following figure.

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Shadow: 2 Marks
When light falls on anopaque object, a dark patch is formed on the other side of the object, if a screen is present on the other side. This dark patch is known as the shadow.
Eg:

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Light travels in a straight line. This principle is behind the working of a pinhole camera.

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Shadow Formation: 2 Marks
Types of shadows: 2 Marks
Types of Objects: 1 Mark
A shadow isjust a space or regionwhere there is no light since an opaque object is blocking light rays. The position and intensity of the source of light affects the properties of the type of shadow that is formed.
Light sources can be either point or non-point (extended) in nature. If it is a point source of light, then it forms a simple shadow called an umbra. If it is an extended light source, the shadow is divided into the umbra, penumbra, and antumbra. They can also be used to define levels of darkness, as is sometimes done when dealing with sunspots.
No, only opaque objects can cast a shadow.

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Answer: 1 Mark
Reason: 2 Marks
No, you won't be able to see your reflection in the mirror.
An image is formed when light is reflected by an object and reaches our eye. In the dark room, there is no light, which means there won't be anyreflection of light. Hence, no image will be formed by a mirror in a completely dark room.

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Reason: 3 Marks
Shadows are formed when an object is placed in the path of light and that object does not let the lightpass through it. Shadows are formed on the opposite side of the object.
During morning and evening, the incident angle of the light is very small. Due to this, long shadows are formed in the morning and evening than the noon.