Light waves (chapter 12) Flashcards

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1
Q

What are luminous objects?

A

Objects which emit their own light.

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2
Q

How do we see non-luminous objects?

A

We see non-luminous objects because of the light they reflect.

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3
Q

What happened when a ray of light strike a mirror?

A

angle of incidence = angle of reflection

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4
Q

What is refraction?

A

When a ray of light travel across the border between two different medium, the change in speed cause the ray to change direction.

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5
Q

What is the speed of light in glass?

A

200 million m/s

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6
Q

What happens if the ray strikes the boundary between the two media at 90 degrees?

A

The ray continues without a change of direction.

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7
Q

How is the amount of refraction described?

A

Refraction index

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8
Q

Refraction occurs at —– medium.

A

2

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9
Q

State the formula to find refractive index?

A

n = sin i / sin r

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10
Q

Which object is needed for reflection of rays?

A

Mirror

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11
Q

What are transparent objects?

A
  • Water
  • Ice
  • Glass
  • Diamond
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12
Q

Which surface does regular reflection and diffused reflection occur?

A

Regular reflection - smooth surface
Diffused reflection - rough surface

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13
Q

Which kind of waves doesn’t need medium?

A

EM waves

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14
Q

What is refractive index?

A

Amount that use to describe how much do different materials can bend rays of light.

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15
Q

What is total internal reflection?

A

Total internal reflection occurs when rays of light are travelling towards a boundary with a less optically dense medium.

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16
Q

What is critical angle?

A

The critical angle is the smallest possible angle of incidence at which light rays are totally internally reflected.

17
Q

What happen when Angle of incidence (i) is greater than the critical angle?

A

All the light is internally reflected at the boundary and no light is refracted.

18
Q

What are conditions needed for total internal reflection?

A
  • (i) > (c)
  • Light must travel from more dense to less dense medium
19
Q

What are the equipment to investigate total internal reflection?

A
  • Semi-circular glass box
  • A ray box
20
Q

What is the formula to find critical angle?

A

sin c = 1/ n (refractive index)

21
Q

How much is the critical angle for light passing from glass to air.

A

42 degree

22
Q

Why is it better to use prisms in a periscope?

A

The images produced by prisms are often brighter and clearer than those produced by mirrors.

23
Q

What are the uses of total internal reflection?

A
  • Prismatic periscope
  • Bicycle and car reflectors
  • Binoculars
  • Optical fibers
  • Endoscope
  • Telecommunications
24
Q

How is optical fiber composed of?

A

It is composed of 2 different type of glass which the center has high refraction index glass surrounded by glass with low refraction index.

25
Q

What does each side of a pair of binoculars contain?

A

Two prisms to totally internally reflect the incoming light.

26
Q

How will the binocular without the prisms be like?

A

Without the prisms, the binoculars would have to be very long to obtain large magnifications.

27
Q

How is it make sure that light entering the inner core in optical fiber is always internally reflected?

A

As the fibers are narrow, light entering the inner core always strike the boundary of the two glasses at an angle that is greater than critical angle.

28
Q

What is the benefit of the use of endoscope?

A
  • less stressful for patients
  • usually leads to a more rapid recovery.
29
Q

Why modern telecommunications systems use optical fibers rather than copper wires?

A

Less energy is lost by using optical fibers.

30
Q

How are electrical signals from telephone are converted?

A

They are converted into light energy produced by tiny lasers.

31
Q

What changes the pulses of light back in electrical signals in optical fiber?

A

Light-sensitive detector at the other end.

32
Q

How much is the critical angle for light passing from water to air?

A

49 degree

33
Q

What is the relationship between refractive index (n) and critical angle (c).

A

Inversely proportional

34
Q

What is the relationship between density and refractive index (n).

A

Directly proportional