Find x if
Answers
Answer:
A wire of length = l and resistance = R , if it streched such that its length becomes 3 times more of its initial one. Find the ratio of initial resistance to the newly obtained resistance.
To Find:-
Find the ratio.
Solution:-
Case 1:-
\sf\dashrightarrow \: R = \dfrac { ρl } { A_1 } ⇢R=
A
1
ρl
\sf\dashrightarrow \: R = \dfrac { ρl } { 3A_2 } ⇢R=
3A
2
ρl
. . . . ( 1 )
Case 2:-
\sf\dashrightarrow \: R' = \dfrac { ρ \times 3l } { A_2 } ⇢R
′
=
A
2
ρ×3l
\sf\dashrightarrow \: R' = \dfrac { 3ρl } { A_2 } ⇢R
′
=
A
2
3ρl
. . . . ( 2 )
Now ,
We have do to divide ( 1 )/( 2 ) then we get:-
\sf\dashrightarrow \: \dfrac { R } { R' } = \dfrac { \: \: \dfrac { ρl } { 3A_2 } \: \: } { \dfrac { A_2 } { 3ρl } } ⇢
R
′
R
=
3ρl
A
2
3A
2
ρl
\sf\dashrightarrow \: \dfrac { R } { R' } = \dfrac { ρl } { 3A_2 } \times \dfrac { A_2 } { 3ρl } ⇢
R
′
R
=
3A
2
ρl
×
3ρl
A
2
\sf\dashrightarrow \: \dfrac { R } { R' } = \dfrac {1 } { 9 }⇢
R
′
R
=
9
1
\sf\dashrightarrow \: R : R' = 1 : 9 ⇢R:R
′
=1:9
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