CBSE Class 4 Science Light, Luminous Objects and Shadows Worksheet Set 01

Answer: (c) Moon. The Moon does not make its own light; it reflects the light of the Sun.

Teacher's Note:
1. A source of light gives out its own light.
2. We see the Moon because sunlight bounces off it.

Answer: (b) blocks the path of light. The dark patch behind the object is the shadow.

Teacher's Note:
1. Light travels in straight lines and cannot bend around objects.
2. So the area behind the object gets no light.

Answer: (a) It looks dark whatever the colour of your clothes. A shadow is only a place where light is blocked.

Teacher's Note:
1. A shadow does not copy colours.
2. Its size changes with the position of the light.

Answer: (c) An electric torch that is switched off. A switched-off torch gives no light, so nothing is blocked.

Teacher's Note:
1. A shadow needs a source of light.
2. The other three are all giving light.

Answer: (c) Opaque. Opaque objects do not let any light pass.

Teacher's Note:
1. Wood and metal are opaque.
2. Transparent objects let the most light pass.

Answer: True. Stars make their own light, like the Sun.

Teacher's Note:
1. The Sun is also a star.
2. Things that make their own light are luminous.

Answer: True. We see non-luminous objects when light bounces off them and reaches our eyes.

Teacher's Note:
1. No light reaching the eyes means nothing is seen.
2. This is why a room is dark at night without a lamp.

Answer: False. Light travels in straight lines and cannot bend around objects.

Teacher's Note:
1. That is why shadows form.
2. Light can only pass through transparent or translucent things.

Answer: False. A shadow needs a source of light and an object that blocks it.

Teacher's Note:
1. Without light there is nothing to block.
2. The whole place is simply dark.

Answer: False. Translucent substances allow only some light to pass through.

Teacher's Note:
1. Opaque objects allow none.
2. Frosted glass is translucent.

Answer: The Sun (a candle, a bulb or a star is also correct).

Teacher's Note:
1. Sources of light give out their own light.
2. Natural and man-made sources both exist.

Answer: Reflection.

Teacher's Note:
1. Light bounces off shiny and non-shiny surfaces.
2. It is how we see most things.

Answer: A shadow.

Teacher's Note:
1. It is a dark area behind the object.
2. It needs a source of light.

Answer: A translucent object, such as frosted glass or tracing paper.

Teacher's Note:
1. Only some light passes through it.
2. A transparent object lets you see clearly.

Answer: Luminous objects are objects that give out their own light, such as the Sun, a burning candle and a lit bulb.

Teacher's Note:
1. Non-luminous objects do not make light.
2. They are seen only when they reflect light.

Answer: A translucent substance allows some light to pass through it, but things behind it cannot be seen clearly. Tracing paper and frosted glass are examples.

Teacher's Note:
1. It lies between transparent and opaque.
2. Light is scattered as it passes through.

Answer: Luminous objects give out their own light (the Sun, a candle). Non-luminous objects do not (a book, the Moon); we see them when light reflects from them.

Teacher's Note:
1. The Moon is non-luminous because it only reflects sunlight.
2. Always give examples to support the difference.

Answer: Light travels in straight lines. When an opaque object blocks the path of light, the area behind it gets no light and a dark shadow forms there.

Teacher's Note:
1. A source of light, an opaque object and a screen are needed.
2. The shape of the shadow matches the shape of the object.

Answer: A transparent object lets almost all light pass, so things can be seen clearly through it (clear glass, water). A translucent object lets some light pass and things look blurred (tracing paper, frosted glass).

Teacher's Note:
1. Clarity is the main difference.
2. Think of a clean window and a bathroom window.

Answer: We use clear glass for windows and doors, so that light comes in and we can see outside. We also use it for spectacles and for the windscreens of vehicles.

Teacher's Note:
1. Transparent materials let us see through them.
2. Plastic bottles are another example.

Answer: Opaque objects do not allow any light to pass through them. A wooden door and a metal plate are examples.

Teacher's Note:
1. Opaque objects make the darkest shadows.
2. They block light completely.

Answer: At noon, when the Sun is almost overhead.

Teacher's Note:
1. The shadow is longest in the early morning and evening.
2. The length depends on the height of the Sun.

Answer: No. If light could bend around objects, it would reach the area behind them and no dark patch would form.

Teacher's Note:
1. Shadows exist because light moves in straight lines.
2. This is a thinking question; give a reason.

Answer: No. We see an object only when light from it enters our eyes, and this object sends out no light at all.

Teacher's Note:
1. Seeing needs light to reach the eyes.
2. Such an object would look completely black.