Which of the following diagrams does illustrate what happens when a ray of light meets an air-water boundary? a
A
b
B
c
C
d
D
Question 11 (1 point)
The diagram shows light travelling from air into glass.

Four angles V , W , X and Y are shown.

Which formula is used to calculate the refractive index , n , of the glass ?

a
n = sin w / sin x
b
n = sin v / sin y
c
n = sin w / sin y
d
n = sin v / sin x
Question 12 (1 point)
Light travels in a vacuum and then enters a glass block. The speed of the light in the glass block is 2.0 × 10 8 m s -1.

Which statement about the speed of light is correct?

a
The speed in the glass is 1.5 times the speed in the vacuum
b
The speed in the vacuum is 1.5 times the speed in the glass
c
The speed in the vacuum is same as the speed in the glass
d
The speed in the glass is 1.0 × 10 8 times the speed in a vacuum.
Question 13 (1 point)
A ray of light in air strikes a glass boundary at an angle of 0° . The light will be:

a
totally reflected
b
undeviated
c
refracted at an unknown angle
d
refracted at 90 degrees to the normal
Question 14 (1 point)

Light travelling in glass is incident on the glass-air boundary as shown. The angle of incident of the light is greater than the critical angle.

Which arrow shows the direction of the light after it is incident on the boundary ?

a
A
b
B
c
C
d
D
Question 15 (1 point)
Which diagram best shows the path taken by the ray of light through the rectangular glass block ?

a
A
b
B
c
C
d
D
Question 16 (1 point)
A ray of light entering the eye changes direction. Thia effect is called:

a
Refraction
b
Interference
c
Reflection
d
Diffraction
Question 17 (1 point)
Total internal reflection in a medium occurs only when the angle of incidence:

a
equals the angle of refraction
b
equals 90
c
is less than the critical angle
d
is greater than the critical angle
Question 18 (1 point)
_ Which of the following statements MUST be true if total internal reflection is to occur?

I. The angle of refraction must be 90º

II. The angle of incidence must be equal to the angle of refraction

III. The angle of incidence must be greater than the critical angle

IV. Light must be travelling from one medium to a less optically dense medium.

a
III and IV only
b
I and II only
c
I and III only
d
II and III only
Question 19 (1 point)
A ray of light travels from air to glass as shown.

The speed of light in air is 3.00 x 10 8 m s-1.

What is the speed of light in the glass ?

a
3.00 x 10 8 m/s
b
2.00 x 10 8 m/s
c
4.24 x 10 8 m/s
d
2.12 x 10 8 m/s

  sequence  is a continuous and distinctive band of  stars  that appears on plots of stellar  color  versus  brightness. these color-magnitude plots are known as  hertzsprung–russell diagramsafter their co-developers,  ejnar hertzsprungand  henry norris russell. stars on this band are known as  main-sequence stars  or  dwarf stars. these are the most numerous true stars in the universe, and include the earth's  sun.after condensation and ignition of a star, it generates  thermal energy  in its dense core region through  nuclear fusion  of  hydrogen  into  helium. during this stage of the star's lifetime, it is located on the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and age. the cores of main-sequence stars are in  hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of  gravitational collapse  from the overlying layers. the strong dependence of the rate of energy generation on temperature and pressure to sustain this balance. energy generated at the core makes its way to the surface and is radiated away at the  photosphere. the energy is carried by either  radiation  or  convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.the main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. stars below about 1.5 times the  mass of the sun  (1.5  m☉) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the  proton–proton chain. above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of  carbon,  nitrogen  and  oxygen  as intermediaries in the  cno cycle  that produces helium from hydrogen atoms. main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. below this mass, stars have cores that are entirely radiative with convective zones near the surface. with decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases. main-sequence stars below 0.4  m☉undergo convection throughout their mass. when core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.in general, the more massive a star is, the shorter its lifespan on the main sequence. after the hydrogen fuel at the core has been consumed, the star  evolves  away from the main sequence on the hr diagram, into a  supergiant,  red giant, or directly to a  white dwarf.