A wire is stretched so that its length becomes 6/5 times of its original length. If its original resistance is 25 Ω find its new resistance. Give justification for your answer in each case.
Answers
Answer:
A wire is stretched so that its length becomes 6/5 times its original length. If its original resistance is 25 ohm find its new resistance and resistivity
Explanation:
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Answer:
here we can see the resistance is 25 ohm .
resistance = 25 ohm
length after stretched = 6/5
length increased = 1/5
here ,
area of cross section is decreased .
1/5 area of cross section decreased .
that means ,
area of cross section = 4/5
we are going to equations :
resistivity = resistance × area of cross section / length
resistance : R
resistivity : p(it is not p , it is rho , icant type it , please use rho )
area of cross section = A
length = l
then we are going to calculate it :
p = R × A / l
in other words we can change this equation :
R = p × l/A
here , R = 25 ohm
25 = p × l / A
this time ( length was increased and area of cross section was decreased )
R = p × (6/5× l) /(4/5A)
then starting calculation :
level of increased = (p × (6/5× l) /(4/5A))/p × l / A
here same values are cancelled .......
we get :
(6/5)/(4/5) = 1.2/0.8
= 12 / 8 = 2.5
here we get it .......
R = 25 × 2.5 = 37.5
RESISTANCE = 37.5 ohm
NOTE : PLEASE USE OMEGA SIGN EXCEPT OHM