Chapter 22 Answer Key: Current, Ohm’s Law and Power

Chapter 22: Current, Ohms Law and Power – Key

22.1 Current & Ohms Law

1.  6.25 x 10¹⁸ e-

2.  2.0 x 10¹⁰ A

3.  0.04 A

4.  0.576 C

5.  3.12 x 10¹² e-

6.  4.8 Ω

7.  0.20 A

8.  24 Ω

9.  250 V

10.  Draws 10A – would trip the circuit

11.  (i)  20 A – Microwave trips the circuit (ii)  5 A over

22.2 Electric Power

1.  19.2 Ω

2.  960 W

3.  0.83 A

4.  8.33 A: will not trip the breaker

5.  83.3 A

6.  8.8 W

7.  3.9 x 10¹⁸ e-

8.  (i)  576 Ω (ii)  0.21 A (iii)  25 W

22.3 Electrical Energy of Batteries

1.  8.64 x 10⁵ W

2.  9600 W or 9.6 kW

3.  6250 s or 1.74 h

4.  94 h

5.  540 A 6.  (i)  8.4 W  (ii)  1.5 x 104 J

22.4 Electric Power & Energy

1.  (i) $1000 (ii)  4.3 years (iii)   $15.6 Billion (iv)  varies

2.  (i)  Cold = 108 kWh    Hot = 2180 kWh (ii)  Cold = $11.⁹⁰  Hot = $239.⁸⁰

3.  1.1 x 106 J/kg 4.  (i) 1.38 GJ (ii) 384 kWh (iii)  $42.²⁴

22.5.1 The Discharge Rate of a Battery

1.  for 400 mA: – 7.0 x 10-5  V/mAh

     for 6000 mA: – 1.6 x 10-4  V/mAh