Two isotopes of iodine are
125 I and 131 I.
53 53
Determine, for these two isotopes, the difference between the constituents of the
nuclei.
[1 mark]
0 1 . 2 A
131 I nuclide undergoes beta (β
–
) decay to form a
...
Two isotopes of iodine are
125 I and 131 I.
53 53
Determine, for these two isotopes, the difference between the constituents of the
nuclei.
[1 mark]
0 1 . 2 A
131 I nuclide undergoes beta (β
–
) decay to form a xenon nuclide.
53
State the nucleon number of the xenon nuclide.
[1 mark]
0 1 . 3 A
125 I nuclide decays by electron capture to form a tellurium nuclide.
53
State two differences between the constituents of the iodine nucleus and the tellurium
nucleus it decays into.
[2 marks]
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7
. Internal conversion is a process in which a nucleus in an excited state can release its
excess energy. In internal conversion all of the excess energy is transferred from the
nucleus to an orbital electron through the electromagnetic force. This orbital electron
is ejected from the atom.
The tellurium nucleus formed in question 01.3 is in an excited state and can undergo
internal conversion.
Discuss three differences between internal conversion and beta (β
–
) decay.
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box
[3 marks]
1
2
3
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0 1
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1
2
Some cars are fitted with a water sensor designed to switch on windscreen wipers
automatically when it rains. Figure 1 shows a simplified diagram of the sensor.
Figure 1
A light ray travels from the light-emitting diode (LED) through the first prism and into
the windscreen. The ray reflects off the surfaces of the windscreen at A, B and C and
then passes through the second prism into the detector.
Do not write
outside the
box
. Suggest how the design ensures that there is no deviation of the ray as it enters the
first prism.
[1 mark]
. Suggest two features of the design that ensure that there is no deviation of the ray as
it leaves the first prism and enters the windscreen glass.
[2 marks]
1
2
0 2
0 2
0 2
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. 3 The refractive index of the windscreen glass is 1.52
Explain why the ray follows the path shown inside the windscreen glass in Figure 1.
Support your answer with a suitable calculation.
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[2 marks]
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0 2
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. 4 When it starts to rain, water droplets form on the outside of the windscreen as shown
in Figure 2.
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Figure 2
The refractive index of water is 1.33
Explain why the presence of water at A causes the intensity of the light at the detector
to decrease.
Support your answer with a suitable calculation.
[2 marks]
0 2
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6
. The refractive index of the windscreen glass can vary by a few per cent across the
thickness of the glass.
Discuss how this variation may affect the path of the ray through the windscreen
glass.
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outside the
box
[2 marks]
. A different design has the LED and the detector further apart. The ray undergoes
more reflections inside the windscreen glass before reaching the detector.
Discuss two ways in which this different design affects the sensitivity of the sensor to
the presence of water droplets.
[2 marks]
1
2
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2
Figure 3 shows an arrangement to investigate diffraction. White light is incident on a
single slit. After leaving the slit, the diffracted light passes through a green filter to
reach the screen.
Figure 3
Do not write
outside the
box
. Describe the pattern produced on the screen.
[2 marks]
. The green filter is replaced with a red filter.
Describe the change in the pattern produced on the screen.
[2 marks]
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