EGR203 Electronic Circuits Assignment 1

  1. Determine the total charge entering a circuit element between t = 1 s and t = 2 s if the current passing through the element is i = 3t2 (amps)

  2. Suppose that the cost of electrical energy is $0.094 per kilowatt hour (Dayton Power and Light, January 2013) and that your electric bill for 30 days is $70 (power usage only, not including other charges or taxes). Assume that the power delivered is constant over the entire 30 days. What is the power in watts? If a voltage of 110 V supplies this power, what current flows? Part of your electrical load is a 60-W light that is on continuously. By what percentage can your energy consumption be reduced by turning this light off?

  3. A typical alkaline 9-V battery that costs $1.95 is capable of delivering a current of 50 mA for a period of 10 hours. Determine the cost of the energy delivered by this battery per kilowatt hour. Compare to the $0.094 per kilowatt hour for energy purchased from Dayton Power and Light.

  4. Your resistor is color coded green-blue-red. What is its nominal resistance?

  5. Suppose we measured a resistance of about 1.4 Ω across a graphite stick, used calipers to measure the cross-section of the stick (7 mm by 5 mm) and measured the distance between the multimeter test leads (54 mm). Based on these measurements, calculate the bulk resistivity of the graphic stick.

  6. Given a resistor of 110 Ω connected to a 12 V battery, find the power absorbed by the resistor. What are the consequences if the resistor is rated at one-quarter watt?

  7. Suppose we have a 220-Ω resistor rated at one-half watt. What is the maximum voltage we can apply to the resistor without exceeding its power rating?

  8. Suppose your multimeter is fused for 300 mA. You want to measure current through a resistor via a 9-volt battery. What is the minimum resistance such that the current is less than 200 mA?

  9. A typical lead acid storage battery has a mass of 30 kg. Starting from a fully charged state, it can supply 5 A for 24 hours with a terminal voltage of 12 V before it is discharged. a. If the energy stored in the fully charged battery is used to lift the battery with 100-percent efficiency, what height is attained? Assume that the acceleration due to gravity is 9.8 m/s2 and us constant with height. b. If the stored energy is used to accelerate the battery with 100-percent efficiency, what velocity is attained? c. Gasoline contains about 4.5 × 107 J/kg. Compare this with the energy content per unit mass for the fully charged battery.

  10. A typical “deep-cycle” battery (used for electric trolling motors for fishing boats) is capable of delivering 12.6 V and 10 A for a period of 10 hours. How much charge (in columbs) flows through the battery in this interval? How much energy does the battery deliver?

  11. A copper wire has a diameter of 2.05 mm and carries a current of 5 A due solely to electrons. (these values are common in residential wiring.) Each electron is has a charge of of -1.6 × 10-19 C. Given that the free electron (those electrons capable of moving through the copper) concentration in copper is 1029 electrons/m3, find the average velocity of the electrons in the wire.

  12. Given two resistors, R1 = 1.5 kΩ and R2= 2.7 kΩ, find the resistance in series and in parallel.

Maintained by John Loomis, last updated 19 January 2013