A 20cm long uniform wire of resistance 5ohm is stretched to a uniform wire of 40cm length the resistance of wire (ohm) will be.
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Resistance of wire will be 20 Ω
Explanation:
Resistance of a wire is given by the formula
R=ρlA
R=ρlA=ρlA×(ll)=ρl2Al=ρl2V
From above relation, R∝l2 [∵ Resistivity (ρ) and Volume (V) of wire will be same even after stretching].
R2R1=(l2l1)2
R2=R1×(l2l1)2
R2=5 Ω×(40cm20cm)2
R2=20 Ω
Explanation:
Resistance of a wire is given by the formula
R=ρlA
R=ρlA=ρlA×(ll)=ρl2Al=ρl2V
From above relation, R∝l2 [∵ Resistivity (ρ) and Volume (V) of wire will be same even after stretching].
R2R1=(l2l1)2
R2=R1×(l2l1)2
R2=5 Ω×(40cm20cm)2
R2=20 Ω
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