College Physics for AP® Courses

# Chapter 19

### Problems & Exercises

1.

42.8

4.

$1 . 00 × 10 5 K 1 . 00 × 10 5 K size 12{1 "." "00"×"10" rSup { size 8{5} } " K"} {}$

6.

(a) $4×104 W4×104 W size 12{4×"10" rSup { size 8{4} } " W"} {}$

(b) A defibrillator does not cause serious burns because the skin conducts electricity well at high voltages, like those used in defibrillators. The gel used aids in the transfer of energy to the body, and the skin doesn’t absorb the energy, but rather lets it pass through to the heart.

8.

(a) $7.40×103 C7.40×103 C size 12{7 "." "40"×"10" rSup { size 8{3} } " C"} {}$

(b) $1.54×1020 electrons per second1.54×1020 electrons per second size 12{1 "." "54"×"10" rSup { size 8{"20"} } " electrons"} {}$

9.

$3.89 × 10 6 C 3.89 × 10 6 C$

11.

(a) $1.44 × 10 12 V 1.44 × 10 12 V$

(b) This voltage is very high. A 10.0 cm diameter sphere could never maintain this voltage; it would discharge.

(c) An 8.00 C charge is more charge than can reasonably be accumulated on a sphere of that size.

15.

(a) $3.00 kV3.00 kV size 12{3 "." "00"" kV"} {}$

(b) $750 V750 V size 12{"750"" V"} {}$

17.

(a) No. The electric field strength between the plates is $2.5×106V/m, 2.5×106V/m, size 12{2.5 times "10" rSup { size 8{6} } "V/m"} {}$ which is lower than the breakdown strength for air ($3.0×106V/m3.0×106V/m size 12{3 times "10" rSup { size 8{6} } "V/m"} {}$).

(b) 1.7 mm

19.

44.0 mV

21.

$15 kV 15 kV size 12{"15 kV"} {}$

23.

(a) $800 KeV800 KeV size 12{"800"" KeV"} {}$

(b) $25.0 km25.0 km size 12{"25" "." 0" km"} {}$

24.

144 V

26.

(a) 1.80 km

(b) A charge of 1 C is a very large amount of charge; a sphere of radius 1.80 km is not practical.

28.

$–2 . 22 × 10 – 13 C –2 . 22 × 10 – 13 C size 12{2 "." "22" times "10" rSup { size 8{ - 13} } C} {}$

30.

(a) $3 . 31 × 10 6 V 3 . 31 × 10 6 V size 12{3 "." "31" times "10" rSup { size 8{6} } V} {}$

(b) 152 MeV

32.

(a) $2 . 78 × 10 - 7 C 2 . 78 × 10 - 7 C size 12{2 "." "78" times "10" rSup { size 8{-7} } C} {}$

(b) $2 . 00 × 10 - 10 C 2 . 00 × 10 - 10 C size 12{2 "." "00" times "10" rSup { size 8{-10} } C} {}$

35.

(a) $2.96×109m/s2.96×109m/s$

(b) This velocity is far too great. It is faster than the speed of light.

(c) The assumption that the speed of the electron is far less than that of light and that the problem does not require a relativistic treatment produces an answer greater than the speed of light.

46.

$21 . 6 mC 21 . 6 mC size 12{"21" "." 6" mC"} {}$

48.

$80 . 0 mC 80 . 0 mC size 12{"80" "." 0" mC"} {}$

50.

20.0 kV

52.

$667 pF 667 pF size 12{"667"" pF"} {}$

54.

(a) $4.4 µF4.4 µF size 12{4 "." "4 "mF} {}$

(b) $4.0×10–5 C4.0×10–5 C size 12{4 "." 0 times "10" rSup { size 8{ - 5} } " C"} {}$

56.

(a) 14.2 kV

(b) The voltage is unreasonably large, more than 100 times the breakdown voltage of nylon.

(c) The assumed charge is unreasonably large and cannot be stored in a capacitor of these dimensions.

57.

$0.293 μF 0.293 μF$

59.

$3.08 µF3.08 µF size 12{3 "." "08" µF } {}$ in series combination, $13.0 µF13.0 µF size 12{"13" "." "0 "µF} {}$ in parallel combination

60.

$2 . 79 µF 2 . 79 µF size 12{2 "." "79"" µF"} {}$

62.

(a) $–3.00 µF–3.00 µF size 12{8 "." "00" mF} {}$

(b) You cannot have a negative value of capacitance.

(c) The assumption that the capacitors were hooked up in parallel, rather than in series, was incorrect. A parallel connection always produces a greater capacitance, while here a smaller capacitance was assumed. This could happen only if the capacitors are connected in series.

63.

(a) $405 J 405 J$

(b) $90.0 mC 90.0 mC$

64.

(a) 3.16 kV

(b) 25.3 mC

66.

(a) $1.42 × 10 −5 C 1.42 × 10 −5 C$, $6.38 × 10 −5 J 6.38 × 10 −5 J$

(b) $8.46 × 10 −5 C 8.46 × 10 −5 C$, $3.81 × 10 −4 J 3.81 × 10 −4 J$

67.

(a) $4.43×10–9 F4.43×10–9 F size 12{4 "." "43" times "10" rSup { size 8{ - "12"} } " F"} {}$

(b) $0.452 V0.452 V size 12{"0.452"" V"} {}$

(c) $4.52×10–10 J4.52×10–10 J size 12{4 "." "52" times "10" rSup { size 8{ - 7} } " J"} {}$

70.

(a) $133F133F size 12{"133"" F"} {}$

(b) Such a capacitor would be too large to carry with a truck. The size of the capacitor would be enormous.

(c) It is unreasonable to assume that a capacitor can store the amount of energy needed.

### Test Prep for AP® Courses

1.

(d)

3.

(b)

5.

(c)

7.

(a)

9.

(b)

11.

(b)

13.

(a)

15.

(c)

17.

(b)

19.

(a)

21.

(d)

23.

(d)

25.

(a)

27.

(b)

29.

(c)

31.

(d)

33.

(a)

35.

(c)

37.

(c)

39.

(b)

41.

(a)

43.

(d)

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