Chapter 20 Answer Key: Electrostatic Fields and Forces

Chapter 20: Electrostatic Fields & Forces (Point Charges) – Key

 

20.1 Electrostatic Forces

1.  (i)  has extra electrons (ii)  6.25 x 106 e-

2.  Repulsive force of 7.2 x 10-4 N

3.  Attractive force of 8.24 x 10-8 N  4.  3.0 x 10-3 m

5.  1st excited   5.12 x 10-9 N   3rd excited   3.2 x 10-10 N

6.  9.03 x 1022 m/s2

7.  (i)  2.0 x 10-5 m/s2 (ii)  4.03 x 107 e-

8.   1.04 x 1024 m/s2 (electron) ac = 1.41 x 1020 m/s2 (core)

9.  d = 1.61 m

10.  d = 5.1 m

 

20.2 Electric Fields (Point Charges)

1.  5.15 x 1011 N/C (away)

2.  3.6 N/C away from Sphere

3.  (i)  8.0 x 10-14 N     (ii)  2.4 x 1012 m/s2

4.  1.02 x 10-7 N/C upwards

5.  (i)  1.6 x 10-15 N     (ii)  1.76 x 1015 m/s2

6.  5.4 x 10-5 m

7.  5.6 x 10-5 N/C

8.  8.2 x 10-8 N

9.  7.1 x 108 N/C away

 

20.3 Hydrogen Atom

1.  (i)  1.02 x 10-9 N      (ii)  2.18 x 106 m/s (iii)  1.99 x 10-24 N/C

2.  Fel = Fc = 0.657 µN

 

 

20.4  Electric Potential

1.  V = – 27.2 J/C

2.  V =  57.5 J/C

3.  ∆ V = 24.2 J/C

 

20.5.1 Deep space research on hydrogen atoms

1.  (i)   v = 15.9 m/s (ii)  1.15 x 10-28 J

 

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