Question 690: Current Electricity

Question

A wire of a certain material is stretched slowly by ten percent. Its new resistance and specific resistance become respectively

Accepted Answer

$${{\Delta l} \over l} = 0.1$$  $$ 	herefore $$ $$l = 1.1$$
but the area also decreases by 0.1.
mass = $$ho lA = Vho $$,  $$\ln l + \ln A = \ln $$ mass.
$$ 	herefore $$ $${{\Delta l} \over l} + {{\Delta A} \over A} = 0 \Rightarrow {{\Delta l} \over l} = {{ - \Delta A} \over A}$$
Length increases by 0.1, resistance increases, area decreases by 0.1, then also resistance will increase. Total increase in resistance is approximately 1.2 times, due to increase in length and decrease in area. But specific resistance does not change.

Answer

both remain the same

Answer

1.1 times, 1.1 times

Answer

1.2 times, 1.1 times

Answer

1.21 times, same

Current Electricity

A wire of a certain material is stretched slowly by ten percent. Its new resistance and specific resistance become respectively

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