Answers

1. N/C or V/m

2. see page

3. E = F/Q   so   F = E Q = 3 x 10⁹  x  1.6 x 10^-19  =  4.8 x 10^-10N

4. work it out

5. F = k Q₁ Q₂ / r²    =      9 x 10⁹  (1.6 x 10^-19)² / (2 x 10^-15)² =  57.6N

6. F = k Q₁ Q₂ / r²    =   9 x 10⁹  (50 x 10^-6  x  50 x 1.6 x 10^-19) / 0.5² = 1.44 x 10^-11N

7.

a) E = k Q / r2 =    9 x 10⁹  x 200 x 10^-3  /  0.2²  =  4.5 x 10¹⁰ N/C

b)

c) F = E Q  = 1.125 x 10¹⁰  x  5 x 10^-9 = 56.3 N

8.

a) E = V / d  =  500 / 0.2 = 2,500 V/m

b) see page

c) F = E Q =  2,500 x 5 x 10^-9  = 1.25 x 10^-5 N

d) W = F x d = 1.25 x 10^-5  x  0.2 = 2.5 x 10^-6 J      OR     W = Q x V  =  5 x 10^-9  x 500 = 2.5 x 10^-6 J

9.

a) E = V / d  =  500,000 / 50  =  10,000 V/m

b) F = E Q = 10,000 x 12.8 x 10^-19  =  12.8 x 10^-15 N

10.

a) V = k q / r  =  9 x 10⁹ x 1.6 x10^-19 / 0.5 x 10^-10  =  28.8 J/C

b) EPE = q V  =  -1.6 x 10^-19  x  28.8  =  - 4.61 x 10^-18 J

c) work required = EPE

d) the electron has positive kinetic energy

11

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