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12. Anelectron (charge=-1.8 x 1010 C)moves 10 cm on a path perpendicular to the

ID: 1788329 • Letter: 1

Question

12. Anelectron (charge=-1.8 x 1010 C)moves 10 cm on a path perpendicular to the direction of a unlform electric field of strength 3.0 N/C. How much work is done on the electron In this process? a, 4.8 x 10 b. -4.8 x 10 C. 1.6x 10 J d zero 13. An electric car ls designed to run off a bank of 12-V batteries with total energy storage of 2 x 10" J. If the electric motor draws 8000 W, what is the current delivered to the motor? a668 A b. 444A C. 222 A It takes 10 J of energy to move 2 C of charge from point A to point B. What is the potential diference between points A and B? a. 20 V b. 0.2V d. None of the above A500-W device is connected to a 100-V power source. What current flows through this surface? a. 50,000 A b. 0.2A 15. 5 A None of the above 16. The heating coll of a hot water heater has a resistance of 20 ohm and operates at 210 V ,201-7- What is itspower rating? a. 8.8 x 105 W C. 10.5W 2205 W d. 2940 W

Explanation / Answer

12. W = F . d = F d cos(theta)

theta = 90 deg and cos90 = 0

W = 0 Ans(d)

13. P = V I

8000 = 12 I => I = 666.7 A Ans(a)

14. U = q delta(V)

10 = 2 V

V = 5 J Ans(c)

15. P = V I

I = 500/100 = 5 A Ans(c)

16. P = V^2 / R = 210^2 / 20 = 2205 W  

Ans(b)