EGR203 Electronic Circuits Assignment 1

  1. Find the common frequencies of microwaves used in microwave ovens. If you have a microwave oven, check whether the labels specify the frequency used. You may also use an internet search. Document your source(s) of information.

  2. Suppose that the cost of electrical energy is $0.12 per kilowatt hour and that your electric bill for 30 days is $60 (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 120 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 $0.12 per kilowatt hour for energy purchased from electric utilities in the United States.

  4. 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.

  5. Given a resistor of 80 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?

  6. Suppose we have a 330-Ω resistor rated at one-half watt. What is the maximum voltage we can apply to the resistor without exceeding its power rating?

  7. 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 150 mA?

  8. Convert the following numbers as specified:

    1. (101101101)2 to decimal and hexadecimal
    2. (E4b)16 to decimal
    3. (89)10 to binary and hexadecimal
    4. (BAAB)12 to decimal and hexadecimal
    5. (574)8 to decimal and hexadecimal
    6. (959)10 to duodecimal (base 12)

  9. Convert the decimal number 1045 to

    1. hexadecimal
    2. octal
    3. binary

  10. In the duodecimal system, find

    1. the largest single-digit symbol (following the practice of hexadecimal A-F)
    2. the range of decimal numbers that can be represented by three duodecimal digits.
    3. the duodecimal number corresponding to 5710

  11. Find

    1. the range of unsigned decimal numbers that can be represented by 10 bits
    2. the range of signed decimal numbers that can be represented by 10 bits
    3. the range of hexadecimal digits that can be represented by 10 bits.
    4. why the number of bytes represented by a binary one following by 10 zeros is called a kilobyte.

Maintained by John Loomis, last updated 6 January 2010