Practice Quiz 61)The resistivity of a 100 m long copper wire is 1.7210!" #m. $f the cross sectional area of the wire is 610!6 m2% what is its resistance& ') 0.( # )) ( # *) (0 # +) (00 # 'nswer, ' 2)The length of a certain wire is -ou.le- an- at the same time its ra-ius is re-uce- .y a factor of 2. /hat is the change in the resistance of this wire& ') $t is -ou.le-. )) $t is 0ua-ruple-. *) $t increases .y a factor of 6. +) $t increases .y a factor of ". 'nswer, + ()The length of a certain wire is halve- while the ra-ius is -ou.le-. /hat is the change in the resistance of this wire& ') $t stays the same. )) $t is re-uce- .y a factor of 2. *) $t is re-uce- .y a factor of ". +) $t is 0ua-ruple-. 'nswer, * 1)' 100!/ light .ul. is connecte- to a 110!2 source. /hat is the resistance of this .ul.& ') 100 # )) ".0010!( # *) 121 # +) 212 # 'nswer, * 3)' 100 2 +* signal is applie- to four resistors as shown in 4igure 1. The values of the resistors are 20 #% 10 #% 60 #% an- "0 #. /hat is the voltage across the 10 # resistor& ') 20 2 )) 10 2 *) 60 2 +) "0 2 'nswer, ' 6)Three resistors of values 2 #% 6 # an- 12 # are connecte- across a +* voltage source as shown in 4igure !2. $f the total current through the circuit is 2.0 '% what is the applie- voltage& ') 6.0 2 )) 2.0 2 *) 2.7 2 +) 1.3 2 'nswer, *7)Three 2.0!# resistors are connecte- across the si-es of an e0uilateral triangle ')* as shown in 4igure (. /hat is the e0uivalent resistance .etween any two points% ')% )*% or '*% of this circuit& ') 2.0 # )) 6.0 # *) 1.( # +) 1.( # 'nswer, + ")$-entify the 5unction no-es in the circuit shown in 4igure 1. ') ' an- ) )) + an- 6 *) ' an- 6 +) * an- 4 'nswer, + 7)/hich of the following e0uations represents a 8irchhoff9s voltage rule for the circuit shown a.ove& ') !6 2 : 2 2 ! ;6#)i( < 0 2 )) :1 2 ! ;"#)i2 ! ;12#)i1 < 0 2 *) !;"#)i2 : 1 2 : 6 2 : ;12#)i1 < 0 2 +) :6 2 ! ;12#)i1 ! ;"#)i2 : 1 2 < 0 2 'nswer, +"7)' capacitor C is connecte- in series with a resistor R across a .attery an- an open switch. $f a secon- capacitor of capacitance 2C is connecte- in parallel to the first% the time constant of the new RC circuit will .e ') the same as .efore. )) twice as large as .efore. *) three times a large as .efore. +) one!half as large as .efore. 'nswer, *