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16 Cards in this Set
- Front
- Back
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What is light? |
It is a form of electromagnetic radiation. |
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What do you mean by reflection of light? |
When a ray of light falls on the surface of a mirror or shining object, it bounces back in the same medium. This is called reflection of light. |
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What do you mean by electromagnetic radiation? |
A form of energy that can travel through air and space and travels in the form of waves that have some properties of electricity and magnetism. Example: Heat and radio waves. |
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What is a shadow? How is a shadow formed? |
A shadow is an image of an object. A shadow is formed when light is completely or partially blocked by an object. |
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State the laws of reflection. |
• Incident ray, reflected ray, and normal drawn at point of incidence to the reflecting surface always lie in the same plane. • Angle of incidence is always equal to the angle of reflection. |
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Distinguish between a real image and a virtual image. |
Real image: • It is formed by actual intersection of rays. • It can be taken on a screen. Virtual image: • It is formed when rays appear to intersect. • It cannot be taken on a screen. |
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What is refraction? |
The bending of a light ray on the surface of separation of media, when travels from one medium to another medium is called refraction. |
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Why do we observe all the colours when the light passes through the prism? |
A ray of white light of seven colours which cannot be seen with our eyes, when passes through the prism, the speed of each colour is reduced by different amounts. This means that they refract by different amounts and spread out, so we can see the colours. |
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What do you mean by a spectrum? |
The bands of coloured light seen when a prism disperses sunlight. The colours are red, orange, yellow, green, blue, indigo, violet. |
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Why is a periscope useful on a submarine? |
It allows the submarine to remain under the surface of water undetected by a ship's crew while one of the submarines crew views the surface. |
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Objects that reflect all the colours in sunlight: |
White objects Example: paper, shirt |
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Objects that absorb all the colours in sunlight: |
Black objects Example: tyres, shoes |
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Which primary colours overlap to produce: a) Yellow b) Magenta c) Cyan d) white light |
a) Red and green b) Red and blue c) Green and blue d) Red, green and blue |
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What are coloured filters? |
Coloured plastic or glass sheets that can filter the colours in light. They absorb some of the colours and allow others to pass through, producing different coloured light.
For example: blue filter allows only blue light to pass through
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Why do different objects have different colours? |
Objects have different colours because they absorb some colours and reflect or transmit other colours. |
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What is a prism? |
A prism is a transparent plastic or glass object with smooth flat sides which can refract light. |
