UNIVERSITY OF MASSACHUSETTS DARTMOUTH
COLLEGE OF ENGINEERING
EGR 101 INTRODUCTION TO ENGINEERING I
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This assignment is due Thursday, February 21, 2013.
Use engineering papers.
Show all of your steps.
Present your work neatly and clearly.
Box your final answers.
Problem 1
What is the diameter in mm of a resistor made of gold, which is 0.1 m long and has a
resistance of 10m ? Use Table 1.3 for properties.
Problem 2
A 1.784-mm diameter wire that is 50 cm long has a resistor of 24.6m . What material
properties does this resistor match closely those listed in Table 1.3?
Problem 3
For comparison of two types of resistors it is advantageous to use RA   L instead of
L
R   . That is, you can compare one resistor of type 1 ( R1 A1  1L1 ) with another
A
R A
 L
resistor of type 2 ( R2 A2  2 L2 ) by expressing the ratio 2 2  2 2 .
R1 A1 1 L1
 Calculate the resistance ratio of a wire (type 2) to one whose diameter is tripled
and length is halved (type 1).
 Find the resistance ratio of aluminum (type 2) to that of gold (type 1) for two
wires of the same length and diameter.
 Find the diameter ratio of aluminum (type 2) to that of gold (type 1) for the same
length and for an aluminum resistance that is one-half that of gold.
Problem 4
A battery provides a total charge of Q  50  C in 3ms .
 What is the current in mA?
 If the battery voltage is 240V, what is the energy generated in mJ, over this time
period?
 What is the power in mW?
Problem 5
A 10-Volt battery provides 3.5 J of energy to a load.
 How much charge in C does the battery provide?
 What is the number of electrons in that charge?
 What is current in mA if the charge is delivered over a period of 10 s?