Chapter 21 Answer Key: Uniform Electric Fields

Chapter 21: Uniform Electric Fields – Key

21.1 Energy Change of Charge moving through a Uniform Electric Field

1.  3.5 x 10⁸ J

2.  0.225 J

3.  (i)  2.4 x 10^-15 J (ii) 15 000 eV

4.  5000 eV or 5 keV

21.2 Uniform Electric Fields (Parallel Charged Plates)

1.  0.04 m

2.  630 V

3.  700 N/C

4.  (i)  2000 N/C (ii)  2.0 x 10^-5 N (iii)  10-6 J  or 1 µJ

5.  (i)  50 000 N/C (ii)  2000 V

6.  (i)  90 V (ii)  6.0 x 10^-8 N (iii)  3.0 x 10^-9 J

7.  (i)  5.0 x 10^-10 N (ii)  5.0 x 10^-12 J  8.  285 V  (≈ 300 V)

21.3 Energy, Momentum & Charged Particles

1.  10^-24 Ns

2.  5.49 x 10^-19 J or 3.43 eV

3.  0.51 m

4.  (i)  5.47 x 10^-23 Ns South  (ii)  5.47 x 10^-17 N

5.  23.5 m

6.  (i)  5.93 x 10⁶ m/s  (ii)  183 000 eV or 0.183 MeV

7.  (i)  0.0125 m (ii)  0.0125 m

8.  (i)  7.64 x 10^-24 Ns (ii)  3.27 x 10^-22 Ns

9.  9.4 x 10⁹ m/s,  around 31 times the speed of light (≈ 31 c)

10.  2.56 x 10^-5 m   (or 25.6 µm)

21.4.1 The Millikan Oil Drop Experiment

1.  First estimated mass of the electron:  me- = 1.22 x 10^-30 kg

21.4.2 An Early Cathode Ray Tube (CRT)

1.  t = 1.1 x 10^-8 s  or   11 ns

21.4.3 Relativistic Charged Particles

1.  v = 2.44 x 10⁸ m/s or 0.81c