Page 288 - Schaum's Outline of Theory and Problems of Applied Physics

CHAP. 23] ELECTRICITY 273

23.3. The electric force between two protons
(a) is weaker than the gravitational force between them
(b) is equal to the gravitational force between them
(c) is stronger than the gravitational force between them
(d) any of the above, depending on the distance between the protons

23.4. The electrons in an atom
(a) are permanently bound to it
(b) are some distance from the nucleus
(c) have more mass than the nucleus
(d) may have positive or negative charges

23.5. The electric field at a point is equal in magnitude to
(a) the number of electric field lines there
(b) the electric charge there
(c) the force a charge of1Cwould experience there
(d) the force an electron would experience there

23.6. The same potential difference is used to accelerate a proton and an electron. Afterward
(a) the proton has the higher velocity
(b) the electron has the higher velocity
(c) the proton has more KE
(d) the electron has more KE

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23.7. If 10 electrons are added to a neutral object, its charge will be
(a) −1.6 × 10 −24 C (c) +1.6 × 10 −24 C
(b) −1.6 × 10 −14 C (d) +1.6 × 10 −14 C

23.8. When they are 80 mm apart, two charges attract each other with a force of 4.0 × 10 −6 N. When the same charges
are 20 mm apart, the force between them is
(a) 1.6 × 10 −6 N (c) 1.6 × 10 −5 N
(b) 8.0 × 10 −6 N (d) 6.4 × 10 −5 N

23.9. Two charges of +2.0 × 10 −9 C that are 3.0 mm apart repel each other with a force of
3
(a) 4 × 10 −9 N (c) 6 × 10 N
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(b) 4 × 10 −3 N (d) 3.6 × 10 N
23.10. The force on a proton in an electric field of 1.0 kV/m is
(a) 2.6 × 10 −35 N (c) 1.6 × 10 −16 N
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(b) 1.6 × 10 −22 N (d) 6.3 × 10 N
23.11. Ten millimeters from a certain charge its electric field is 10 kV/m. The magnitude of the field 20 mm from the
charge is
(a) 2.5 kV/m (c) 7.1 kV/m
(b) 5.0 kV/m (d) 10 kV/m

23.12. An electric force of 1.0 × 10 −5 N acts on a charge of 5.0 × 10 −10 C that is between two parallel metal plates 4.0 mm
apart. The potential difference between the plates is
(a)1.25 × 10 −12 V (c)80 V
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(b)32 V (d)1.6 × 10 V