A hair dryer carries a current of 13.5 A when the operating voltage is 120.0 V.

Question

A hair dryer carries a current of 13.5 A when the operating voltage is 120.0 V. A) What is the resistance of the dryer? _____ B) What amount of charge move through the dryer in 10.0 s? _____ C) How many electrons pass through the dryer in 10.0 s? _____ During an experimental investigation, the resistance and temperature of a copper wire were measured as follows: 1.50 times 10^3 Ohm at 20.0 degree C and 3.0 times 10^3 Ohm at 40.0 degree C. Use this data to determine the temperature coefficient of resistivity. _____

Explanation / Answer

from Ohms law

V= IR

R = V/I = 120/13.5 = 8.88 ohm

q= it = 13.5 ( 10) = 135 C

q= ne

n = q/e = 135/1.6 * 10^-19 = 84.375 * 10^19

(2)

R= R0 ( 1+ alpha del T)

3 * 10^3 ohm = ( 1.5 * 10^3 ) ( 1+ ( alpha ( 40-20))

3 * 10^3 ohm =( 1.5 * 10^3 ) + alpha ( 30 * 10^3)

1.5 * 10^3 /30 * 10^3 = alpha

alpha = 5.0 * 10^-2 /C

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