 College Physics for AP® Courses

# Chapter 29

1.

(a) 0.070 eV

(b) 14

3.

(a) $2.21×1034 J2.21×1034 J size 12{2 "." "21" times "10" rSup { size 8{"34"} } " J"} {}$

(b) $2.26×10342.26×1034 size 12{2 "." "26" times "10" rSup { size 8{"34"} } } {}$

(c) No

4.

263 nm

6.

3.69 eV

8.

0.483 eV

10.

2.25 eV

12.

(a) 264 nm

(b) Ultraviolet

14.

$1.95 × 10 6 m/s 1.95 × 10 6 m/s size 12{1 "." "95" times "10" rSup { size 8{6} } " m/sec"} {}$

16.

(a) $4.02×1015/s4.02×1015/s size 12{4 "." "02" times "10" rSup { size 8{"15"} } "/s"} {}$

(b) 0.256 mW

18.

(a) $–1.90 eV–1.90 eV$

(b) Negative kinetic energy

(c) That the electrons would be knocked free.

20.

$6.34 × 10 − 9 eV 6.34 × 10 − 9 eV size 12{6 "." "34" times "10" rSup { size 8{ - 9} } " eV"} {}$, $1.01 × 10 − 27 J 1.01 × 10 − 27 J size 12{6 "." "34" times "10" rSup { size 8{ - 9} } " eV"} {}$

22.

$2 . 42 × 10 20 Hz 2 . 42 × 10 20 Hz size 12{2 "." "42" times "10" rSup { size 8{"20"} } " Hz"} {}$

24.

hc = 6.62607 × 10 − 34 J ⋅ s 2.99792 × 10 8 m/s 10 9 nm 1 m 1.00000 eV 1.60218 × 10 − 19 J = 1239.84 eV ⋅ nm ≈ 1240 eV ⋅ nm hc = 6.62607 × 10 − 34 J ⋅ s 2.99792 × 10 8 m/s 10 9 nm 1 m 1.00000 eV 1.60218 × 10 − 19 J = 1239.84 eV ⋅ nm ≈ 1240 eV ⋅ nm alignl { stack { size 12{ ital "hc"= left (6 "." "62607" times "10" rSup { size 8{ - "34"} } J cdot s right ) left (2 "." "99792" times "10" rSup { size 8{8} } "m/s" right ) left ( { {"10" rSup { size 8{9} } "nm"} over {1m} } right ) left ( { {1 "." "00000""eV"} over {1 "." "60218" times "10" rSup { size 8{ - "19"} } J} } right )} {} # ="1239" "." "84 eV" cdot "nm" {} # approx "1240 eV" cdot "nm" {} } } {}

26.

(a) 0.0829 eV

(b) 121

(c) 1.24 MeV

(d) $1.24×1051.24×105 size 12{2 "." "24" times "10" rSup { size 8{5} } } {}$

28.

(a) $25.0 × 103 eV 25.0 × 103 eV size 12{" 25 " times " 10" rSup { size 8{3} } " eV"} {}$

(b) $6.04 × 1018 Hz 6.04 × 1018 Hz size 12{" 6" "." "04 " times " 10" rSup { size 8{"18"} } " Hz"} {}$

30.

(a) 2.69

(b) 0.371

32.

(a) $1.25 × 1013 photons/s 1.25 × 1013 photons/s size 12{" 1" "." "25 " times " 10" rSup { size 8{"13"} } " photons/s"} {}$

(b) 997 km

34.

$8.33 × 10 13 photons/s 8.33 × 10 13 photons/s size 12{" 8" "." "33 " times " 10" rSup { size 8{"13"} } " photons/s"} {}$

36.

181 km

38.

(a) $1.66 × 10 − 32 kg ⋅ m/s 1.66 × 10 − 32 kg ⋅ m/s size 12{1 "." "66" times "10" rSup { size 8{ - "32"} } "kg" cdot "m/s"} {}$

(b) The wavelength of microwave photons is large, so the momentum they carry is very small.

40.

(a) 13.3 μm

(b) $9.38×10-29.38×10-2$ eV

42.

(a) $2.65×10−28kg⋅m/s2.65×10−28kg⋅m/s size 12{2 "." "65" times "10" rSup { size 8{ - "28"} } "kg" cdot "m/s"} {}$

(b) 291 m/s

(c) electron $3.86×10−26 J3.86×10−26 J size 12{3 "." "86" times "10" rSup { size 8{ - "26"} } " J"} {}$, photon $7.96×10−20 J7.96×10−20 J size 12{7 "." "96" times "10" rSup { size 8{ - "20"} } " J"} {}$, ratio $2.06×1062.06×106 size 12{2 "." "06" times "10" rSup { size 8{6} } } {}$

44.

(a) $1.32×10−13 m1.32×10−13 m size 12{1 "." "32" times "10" rSup { size 8{ - "13"} } " m"} {}$

(b) 9.39 MeV

(c) $4.70×10−2 MeV4.70×10−2 MeV size 12{4 "." "70" times "10" rSup { size 8{ - 2} } " MeV"} {}$

46.

$E=γmc2E=γmc2mc2$ and $P=γmuP=γmu$, so

$EP = γmc2 γmu = c2 u . EP = γmc2 γmu = c2 u .$

As the mass of particle approaches zero, its velocity $uu$ will approach $cc$, so that the ratio of energy to momentum in this limit is

$limm→0 E P = c2 c = c limm→0 E P = c2 c = c$

which is consistent with the equation for photon energy.

48.

(a) $3 . 00 × 10 6 W 3 . 00 × 10 6 W size 12{3 "." "00" times "10" rSup { size 8{6} } " W"} {}$

(b) Headlights are way too bright.

(c) Force is too large.

49.

$7.28 × 10 –4 m 7.28 × 10 –4 m size 12{7 "." "28" times "10" rSup { size 8{–4} } " m"} {}$

51.

$6.62 × 10 7 m/s 6.62 × 10 7 m/s size 12{6 "." "62" times "10" rSup { size 8{7} } " m/s"} {}$

53.

$1.32 × 10 –13 m 1.32 × 10 –13 m size 12{6 "." "62" times "10" rSup { size 8{7} } " m/s"} {}$

55.

(a) $6.62×107 m/s6.62×107 m/s size 12{6 "." "62" times "10" rSup { size 8{7} } " m/s"} {}$

(b) $22.9 MeV22.9 MeV$

57.

15.1 keV

59.

(a) 5.29 fm

(b) $4.70×10−12 J4.70×10−12 J size 12{4 "." "70" times "10" rSup { size 8{ - "12"} } " J"} {}$

(c) 29.4 MV

61.

(a) $7.28×1012 m/s7.28×1012 m/s size 12{7 "." "28" times "10" rSup { size 8{"12"} } " m/s"} {}$

(b) This is thousands of times the speed of light (an impossibility).

(c) The assumption that the electron is non-relativistic is unreasonable at this wavelength.

62.

(a) 57.9 m/s

(b) $9.55×10−9 eV9.55×10−9 eV size 12{9 "." "55" times "10" rSup { size 8{ - 9} } " eV"} {}$

(c) From Table 29.1, we see that typical molecular binding energies range from about 1eV to 10 eV, therefore the result in part (b) is approximately 9 orders of magnitude smaller than typical molecular binding energies.

64.

29 nm,

290 times greater

66.

$1 . 10 × 10 − 13 eV 1 . 10 × 10 − 13 eV size 12{1 "." "10" times "10" rSup { size 8{ - "13"} } " eV"} {}$

68.

$3 . 3 × 10 − 22 s 3 . 3 × 10 − 22 s size 12{3 "." 3 times "10" rSup { size 8{ - "22"} } " s"} {}$

70.

$2.66 × 10 − 46 kg 2.66 × 10 − 46 kg size 12{2 "." "66" times "10" rSup { size 8{ - "46"} } " kg"} {}$

72.

0.395 nm

74.

(a) $1.3 × 10 − 19 J 1.3 × 10 − 19 J size 12{1 "." "33" times "10" rSup { size 8{ - "19"} } " J"} {}$

(b) $2 . 1 × 10 23 2 . 1 × 10 23 size 12{2 "." 1 times "10" rSup { size 8{"23"} } } {}$

(c) $1 . 4 × 10 2 s 1 . 4 × 10 2 s size 12{1 "." 4 times "10" rSup { size 8{2} } " s"} {}$

76.

(a) $3.35×105 J3.35×105 J size 12{3 "." "35" times "10" rSup { size 8{5} } " J"} {}$

(b) $1.12×10–3 kg⋅m/s1.12×10–3 kg⋅m/s size 12{1 "." "12" times "10" rSup { size 8{"–3"} } " kg" cdot "m/s"} {}$

(c) $1.12×10–3 m/s1.12×10–3 m/s size 12{1 "." "12" times "10" rSup { size 8{"–3"} } " m/s"} {}$

(d) $6.23×10–7 J6.23×10–7 J size 12{6 "." "23" times "10" rSup { size 8{"–7"} } " J"} {}$

78.

(a) $1.06×1031.06×103 size 12{1 "." "07" times "10" rSup { size 8{3} } } {}$

(b) $5.33×10−16kg⋅m/s5.33×10−16kg⋅m/s size 12{5 "." "34" times "10" rSup { size 8{ - "16"} } "kg" cdot "m/s"} {}$

(c) $1.24×10−18m1.24×10−18m size 12{1 "." "24" times "10" rSup { size 8{ - "18"} } m} {}$

80.

(a) $1 . 62 × 10 3 m/s 1 . 62 × 10 3 m/s size 12{1 "." "62" times "10" rSup { size 8{3} } " m/s"} {}$

(b) $4 . 42 × 10 − 19 J 4 . 42 × 10 − 19 J size 12{4 "." "41" times "10" rSup { size 8{ - "19"} } " J"} {}$ for photon, $1 . 19 × 10 − 24 J 1 . 19 × 10 − 24 J size 12{1 "." "19" times "10" rSup { size 8{ - "24"} } J} {}$ for electron, photon energy is $3 . 71 × 10 5 3 . 71 × 10 5 size 12{3 "." "71" times "10" rSup { size 8{5} } } {}$ times greater

(c) The light is easier to make because 450-nm light is blue light and therefore easy to make. Creating electrons with $7.43 μeV 7.43 μeV size 12{7 "." "43""μeV"} {}$ of energy would not be difficult, but would require a vacuum.

81.

(a) $2 . 30 × 10 − 6 m 2 . 30 × 10 − 6 m size 12{2 "." "30" times "10" rSup { size 8{ - 6} } " m"} {}$

(b) $3 . 20 × 10 − 12 m 3 . 20 × 10 − 12 m size 12{3 "." "20" times "10" rSup { size 8{ - "12"} } m} {}$

83.

$3 . 69 × 10 − 4 ºC 3 . 69 × 10 − 4 ºC size 12{3 "." "69" times "10" rSup { size 8{ - 4} } °C} {}$

85.

(a) 2.00 kJ

(b) $1.33×10−5kg⋅m/s1.33×10−5kg⋅m/s size 12{1 "." "33" times "10" rSup { size 8{ - 5} } `"kg" cdot "m/s"} {}$

(c) $1.33×10−5 N1.33×10−5 N size 12{1 "." "33" times "10" rSup { size 8{ - 5} } " N"} {}$

(d) yes

1.

(b)

3.

(c)

5.

(b)

7.

(c)

9.

(c)

11.

(a)

13.

(a)

15.

(c)

17.

(d)

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