Question

The resistance of a wire of 0.01 cm radius is 10 ohm. If the
resistivity of the material of the wire is 50×10^-8 ohm metre,find the length of the wire.​

Answer 1

Answer:

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Answer 2

$\sf\bold{\blue{Ꭺɳรωεɾ:-}}$

• ℓεɳɠƭɦ (ℓ) σƒ ƭɦε ωเɾε =62.86

$\sf\small{\green{ɠเѵεɳ:-}}$

• ɾεรเรƭαɳcε (Ʀ) = 10 ∅mega
• ɾεรเรƭเѵเƭყ (P) = 50×10^-8 ∅mega
• ɾα∂เµร (r) =0.01cm = 0.01×10^-2 m

$\sf\small{\green{\:ᴛᴏ\:ғɪɴᴅ:-}}$

• ℓεɳɠƭɦ (ℓ) σƒ ƭɦε ωเɾε

$\sf\bold{\blue{\:ғᴏʀᴍᴜʟᴀ\: ᴜsᴇᴅ:-}}$

$R =\frac P{l}{A}$

$\sf\bold{\red{\:ʜᴏᴡ\:ᴛᴏ\:ғɪɴᴅ:-}}$

$\sf\small{\green{\:Ꭺɾεa\:σƒ\: ƭɦε \:ωเɾε}}= π r²$

$=\frac{22}{7}$×(0.01×10^-2)²

$=3.143 × 10^-⁴m²$

ɴᴏᴡ,$Ʀ =P\frac{l}{A}$

$=>l=\frac{Ʀ×A}{P}$

$\sf\small{\pink{\:sᴜʙsᴛɪᴛᴜᴛᴇ\:ᴛʜᴇ\:ʀᴇsᴘᴇᴄᴛɪᴠᴇ\:ᴠᴀʟᴜᴇs:-}}$

$=>l=\frac{10×3.143×10^- ⁴}{50×10^-⁸}$

$=>l=0.6286m$

$\sf\small{\green{=>l=62.86cm}}$