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# Series circuit, propulsion, resistance, power costs, transformer

1. A series circuit consists of 10,000, 20,000, and 30,000 ohm resistors connected in series across a 10-volt battery. Determine the current in the circuit?

2. Determine the propulsion force between two electric charges of 3 x and 7 x separated by a distance of 2 meters. (k=9,000,000,000

3. Determine the power consumed by a light bulb whose hot filament resistance is 240 ohms, when connected to a 120 volt source..

4. A 100 watt light bulb is operated continuously for a period of 10.5 days. Assuming power costs .12Cents per kilowatt-hour, what is the total cost to operate the light?

5. A transformer with 300 loops in primary coil is connected to a 120-V source. How many turns are required, in the secondary coil, to provide an output of 240V?

6. Some electric cars use a process of regenerative braking; that is, they turn electric motor into a generator and recharge the battery when slowing the car. Is it correct to say that energy spent to climb a hill could be completely recovered when returning to the starting location?

7. A viewer observes an object submerged in water. Is the object located at the position of the visual image?

8. Explain Fermats principle of least time.

#### Solution Preview

1. A series circuit consists of 10,000, 20,000, and 30,000 ohm resistors connected in series across a 10-volt battery. Determine the current in the circuit?

Solution:
Total resistance R = 10000 + 20000 + 30000 = 60000
Current in the circuit = V/R = 10/60000 = 1.67 x 10-4

2. Determine the propulsion force between two electric charges of 3 x and 7 x separated by a distance of 2 meters. (k=9,000,000,000

Solution:

K = 9,000,000,000

F = ((9,000,000,000)*(3 x 10^-3)*(7 x 10^-3))/2^2 = 47,250 Newtons

3. Determine the power consumed by a light bulb ...

#### Solution Summary

Series circuit, propulsion, resistance, power costs, transformer and Fermats are examined.

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