1.
In sky, earth and moon are
Correct Answer
A. Opaque
Explanation
The correct answer is "opaque" because both the sky and the earth block the light from passing through them, making them not transparent or translucent. The moon also does not allow light to pass through it, as it does not emit its own light and only reflects the light from the sun, making it opaque as well.
2.
A torch is a
Correct Answer
A. Luminous
Explanation
A torch is considered luminous because it produces its own light. It contains a source of energy, such as a battery or a flame, which emits light when activated. This light allows the torch to illuminate its surroundings and provide visibility in dark or dimly lit areas.
3.
What is needed to see shadow?
Correct Answer
D. All of these
Explanation
To see a shadow, all of the mentioned elements are required. A source of light is necessary to create the shadow, as it emits rays that interact with objects. A screen or surface is needed to project the shadow onto, providing a visible representation. Lastly, an opaque object is essential as it obstructs the path of light, allowing a shadow to form behind it. Therefore, all three components are necessary to observe a shadow.
4.
When the pinhole box is pointing to sun then its shadow will be like
Correct Answer
A. Longest
Explanation
When the pinhole box is pointing towards the sun, the shadow it creates will be the longest. This is because the sun's rays are coming from a single point source, and when the pinhole is aligned with the sun, it allows only a small portion of those rays to pass through, creating a focused beam of light. As a result, the shadow cast by the pinhole box will be elongated and appear longer compared to when it is not aligned with the sun.
5.
Which of the following will not form circular shadow?
Correct Answer
A. Shoe box
Explanation
A shoe box will not form a circular shadow because it is a rectangular shape and does not have a curved surface. In order to form a circular shadow, an object needs to have a curved or circular shape. The ball and circular disk have curved surfaces and will therefore form circular shadows. The ice-cream cone, although it has a pointed tip, still has a curved shape and will also form a circular shadow.
6.
Substances like glass, through which light passes easily, are said to be
Correct Answer
C. Transparent substances
Explanation
Transparent substances are substances that allow light to pass through them easily. This means that light is not absorbed or reflected by the substance, but instead passes through it, making the substance see-through. Glass is a common example of a transparent substance, as it allows light to pass through it without blocking or distorting the view on the other side.
7.
When light rays are stopped by an opaque object then are produced.
Correct Answer
B. Shadow
Explanation
When light rays are stopped by an opaque object, a shadow is produced. This occurs because the opaque object blocks the path of light, preventing it from reaching the surface behind it. As a result, an area of darkness is created on the surface opposite to the source of light. Shadows are formed when light is obstructed, and they can vary in size and shape depending on the position and size of the object blocking the light.
8.
Which one of the following is transparent or allows light to pass through it?
Correct Answer
B. Glass
Explanation
Glass is transparent and allows light to pass through it because of its molecular structure. Unlike other materials, glass is made up of a highly ordered arrangement of atoms, which allows light to pass through without significant scattering or absorption. This property makes glass suitable for use in windows, lenses, and other optical applications.
9.
Which of the following does not have light of its own?
Correct Answer
B. The moon
Explanation
The moon does not emit light of its own but reflects sunlight, making it visible from Earth. A torch and a lamp generate light artificially, while the sun is a natural celestial body that emits light and heat through nuclear fusion processes in its core.
10.
Where will your shadow be when the sun is behind you?
Correct Answer
A. In front of you
Explanation
When the sun is behind you, your shadow will be in front of you. This is because the sun's rays will hit you from behind, causing your shadow to be cast in the opposite direction, which is in front of you.