A wire had a resistance of 20Ω. It was then melted and reduced to one-fifth of its original length and its cross section area was doubled. Find its new resistance.
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Answers
Answered by
0
Answer:
180Ω
Explanation:
Resistance, R=
A
ρl
When length l increases three times, the cross section A will decease three times of previous. So length becomes 3l and cross section becomes A/3.
Now resistance becomes ,R
′
=
πA/3
ρ3l
=9R=9×20=180Ω
Answered by
0
Answer:
180Ω
Resistance, R=
A
ρl
When length l increases three times, the cross section A will decease three times of previous. So length becomes 3l and cross section becomes A/3.
Now resistance becomes ,R
′
=
πA/3
ρ3l
=9R=9×20=180Ω
Explanation:
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