Light

Question 1

What is LIGHT?

Answer 1

LIGHT is a form of electromagnetic radiation that is visible to the human eye. It travels at a constant velocity of 2.998 x10⁸ ms¯¹

Question 2

What is REFRACTION?

Answer 2

REFRACTION is the bending of light as it passes from one medium to another

STS: • Real and apparent depth of fish in water

Question 3

What is the CRITICAL ANGLE?

Answer 3

The CRITICAL ANGLE is the angle of incidence for which refracted rays emerge at 90° to the surface separating two media

Question 4

Define TOTAL INTERNAL REFLECTION (TIR)

Answer 4

TIR is an optical phenomenon that occurs when light travelling from a rarer to a denser medium strikes the denser medium with an angle of incidence greater than the critical angle

STS: • Mirages
• Reflective road signs

Question 5

What is an OPTICAL FIBRE?

Answer 5

An OPTICAL FIBRE is a very thin transparent rod through which light can travel by TIR

STS: • Telecommunications
• Medecine (endoscopes)

Question 6

What is PARALLAX?

Answer 6

PARALLAX is the apparent movement of an object due to relative movement from the observer

Question 7

What is the GRATING CONSTANT?

Answer 7

The GRATING CONSTANT is the distance between two adjacent slits on a grate

Question 8

What is a LENS?

Answer 8

A LENS is a piece of carefully cut transparent material that allows light through it

Question 9

What is the POWER OF A LENS?

Answer 9

The POWER OF A LENS is the reciprocal of its focal length

       P = 1/f

Question 10

What is a SELF-LUMINOUS OBJECT?

Answer 10

A SELF-LUMINOUS OBJECT is an object which produces its own light e.g. the Sun, stars, etc.