Page 289 - Schaum's Outline of Theory and Problems of Applied Physics

274 ELECTRICITY [CHAP. 23

23.13. The potential difference between a certain thundercloud and the ground is 4 MW. During a lightning stroke, 80 C
of charge is transferred between the cloud and the ground. The energy dissipated during the stroke is
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(a) 5 × 10 −6 J (c) 3.2 × 10 J
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(b) 2 × 10 J (d) 3.2 × 10 J
23.14. A storage battery is being charged at a rate of 75 W. If the potential difference across its terminals is 13.6 V, charge
is being transferred between its plates at
(a) 0.18 C/s (c) 5.5 C/s
(b) 2.8 C/s (d) 1020 C/s

Supplementary Problems

23.1. An oxygen atom has 8 protons in its nucleus. (a) How many electrons does this atom contain? (b) How many
electrons does the O 2− ion contain?

23.2. What information is provided by a sketch of the field lines of an electric field?

23.3. Why is it impossible for the field lines of an electric field to cross one another?
23.4. A rod with a charge of +q at one end and −q at the other is placed in a uniform electric field whose direction is
parallel to the rod. How does the rod behave?

23.5. The rod of Prob. 23.4 is placed in a uniform electric field whose direction is perpendicular to the rod. How does the
rod behave?
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23.6. A billion (10 ) electrons are added to a neutral pith ball. What is its charge?
23.7. What is the force between two +1-C charges located 1 m apart?

23.8. What are the magnitude and direction of the force on a charge of +2 × 10 −7 C that is 0.3 m from a charge of
−5 × 10 −7 C?

23.9. Two electrons repel each other with a force of 10 −8 N. How far apart are they?

23.10. Two charges attract each other with a force of 10 −6 N when they are 1 cm apart. How far apart should they be for
the force between them to be (a)10 −4 N and (b)10 −8 N?

23.11. A test charge of +2 × 10 −7 C is located 5 cm to the right of a charge of +1 × 10 −6 C and 10 cm to the left of a
charge of −1 × 10 −6 C. The three charges lie on a straight line. Find the force on the test charge.

23.12. A charge of +1 × 10 −7 C and a charge of +3 × 10 −7 C are 40 cm apart. (a) Where should a charge of +q be placed
on the line between these charges so that no net force acts on it? (b) Where should a charge of −q be so placed?
23.13. How much force is exerted on a charge of 10 −6 C by an electric field of 50 V/m?

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23.14. An electron is present in an electric field of 10 V/m. (a) Find the force on the electron. (b) Find the electron’s
acceleration.
23.15. Two charges of +10 −6 C are located 1 cm apart. (a) What is the force on a charge of +10 −8 C halfway between
them? (b) What is the force on a charge of −10 −8 C at the same place? (c) What must be true of the strength of the
electric field halfway between the two +10 −6 -C charges?