True/False
Indicate whether the
sentence or statement is true or false.
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1. |
The
universal wave equation, v = fl, applies only to transverse waves.
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2. |
Snell’s law in the form n = 
holds for both waves and light.
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3. |
Waves
with shorter wavelength experience more diffraction than waves with
a longer wavelength.
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4. |
For
a given slit, the amount of diffraction depends on the ratio
 .
For observable diffraction,  
1
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5. |
In
a two-point, in-phase interference pattern, increasing the wavelength
of the two sources increases the number of nodal lines.
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6. |
Decreasing the separation of the two-point interference pattern
sources increases the number of nodal lines.
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7. |
Newton’s particle theory provided a satisfactory explanation
for four properties of light: rectilinear propagation, reflection, refraction,
and dispersion. It was weak in its explanation of diffraction and partial
reflection–partial refraction.
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8. |
Early
attempts to demonstrate the interference of light were unsuccessful
because the two sources were too far apart and out of phase and the
frequency of light is very small.
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9. |
Dispersion occurs because the refractive index of light is slightly
higher for red light than it is for violet light.
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10. |
Young’s experiment validated the wave theory of light and
explained all the properties of light.
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Multiple Choice
Identify
the letter of the choice that best completes the statement or answers
the question.
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11. |
A
beam of light travels from a vacuum (c = 3.00 
108 m/s) into a substance at an angle of 45°, with a
frequency of 6.00 
1014 Hz and a speed of 2.13 
108 m/s. The index of refraction of the substance is
a. |
0.707 |
b. |
1.41 |
c. |
1.50 |
d. |
indeterminable, but < 1 |
e. |
indeterminable,
but > 1 |
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12. |
You
observe diffraction in a ripple tank (Figure 1). To increase
the diffraction of the waves in the region beyond the barrier, you consider
the following adjustments:
(i) decreasing the
width of the opening
(ii) decreasing the depth of the
water
(iii) decreasing the frequency of
the source
 Figure 1
The
best adjustment, or combination of adjustments, is
a. |
(i) only |
b. |
(ii) only |
c. |
(iii) only |
d. |
(i) and (iii) only |
e. |
(i),
(ii), and (iii) |
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13. |
Diffraction
by a single slit in a ripple tank can be decreased by
a. |
increasing
the frequency of the source |
b. |
increasing the amplitude of the waves |
c. |
decreasing
the width of the slit |
d. |
decreasing the distance between the wave generator
and the slit |
e. |
using
a longer wavelength |
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14. |
Two
point sources in a ripple tank vibrate in phase at a frequency of 12
Hz to produce waves of wavelength 0.024 m. The difference in path length
from the two point sources to a point on the second nodal line is
a. |
0.6
cm |
b. |
1.2
cm |
c. |
2.4
cm |
d. |
3.6
cm |
e. |
4.8
cm |
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15. |
Two
point sources 4.5 cm apart are vibrating in phase in a ripple tank.
You count exactly 10 nodal lines in the entire interference pattern.
The approximate wavelength of the water waves in the tank is
a. |
0.45
cm |
b. |
1.0
cm |
c. |
1.5
cm |
d. |
10
cm |
e. |
insufficient
data provided |
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16. |
You
observe the wave pattern in Figure 2 as you investigate periodic
waves in a ripple tank. You draw the straight lines shown superimposed
on the figure. The wavelength is
 Figure 2
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17. |
You
wish to continue the same pattern as in question 16, but contemplate
making adjustments:
(i) increasing the frequency of the
waves
(ii) increasing the separation of
the sources
(iii) introducing a phase delay in
S1
The
adjustment, or combination of adjustments, that results in a larger
number of nodal lines is
a. |
(i)
only |
b. |
(ii)
only |
c. |
(iii)
only |
d. |
(i)
and (ii) only |
e. |
(i),
(ii), and (iii) |
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18. |
The
adjustment, or combination of adjustments, in question 17 that results
only in a shift of the nodal lines is
a. |
(i)
only |
b. |
(ii)
only |
c. |
(iii)
only |
d. |
(i)
and (ii) only |
e. |
(i),
(ii), and (iii) |
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19. |
The
particle theory is unable to account for the phenomenon of
a. |
radiation pressure |
b. |
emission |
c. |
interference |
d. |
propagation |
e. |
reflection |
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20. |
The
statement regarding Young’s experiment that is false is
a. |
Diffraction
of light occurs at both slits. |
b. |
Light waves leaving the two slits have a fixed
phase. |
c. |
The interference pattern from this experiment has
a nodal line down the centre of the pattern. |
d. |
The separation of the nodal lines is dependent
on the wavelength of the light. |
e. |
The particle theory was unable to give a satisfactory
explanation of this phenomenon. |
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21. |
In
a double-slit experiment, monochromatic light is used to produce interference
fringes on a screen. The distance between the slits and the screen is
1.50 m. The bright fringes are separated by 0.30 cm. If the screen is
moved so that it is 1.0 m from the slits, the average distance between
adjacent dark fringes will be
a. |
0.20
cm |
b. |
0.30
cm |
c. |
0.45
cm |
d. |
0.67
cm |
e. |
1.5
cm |
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22. |
Ultraviolet
light of wavelength 340 nm falls on a double slit. A fluorescent screen
is placed 2.0 m away. The screen shows dark interference bands 3.4 cm
apart. The distance between the slits is
a. |
2.0
cm |
b. |
0.20
cm |
c. |
0.020
cm |
d. |
0.0020
cm |
e. |
none
of these |
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Figure
3 shows a double-slit pattern produced by a monochromatic source
of pattern (a), which is changed to pattern (b). The following are possible
adjustments:
Figure 3
(i) The frequency
of the source was decreased.
(ii) The frequency of the source
was increased.
(iii) The width of each slit was
increased.
(iv) The separation of the slits
was increased.
(v) The separation of the slits was
decreased.
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23. |
The
adjustment, or combination of adjustments, that explains pattern (b)
is
a. |
(iii)
only |
b. |
(v)
only |
c. |
(i)
and (iii) only |
d. |
(i)
and (v) only |
e. |
(ii)
and (iv) only |
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