A wire has a resistance of 16 w. It is melted and drawn into a wire of half its original length. Calculate the resistance of the new wire.
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Answer:
Answer (Detailed Solution Below)
Option 1 : 4 ohms
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Electric charges and coulomb's law (Basic)
10 Qs. 10 Marks 10 Mins
Detailed Solution
CONCEPT:
Resistance (R): The resistance offered to the flow of current is known as the resistance.
The SI unit of resistance is the ohm (Ω).
Mathematically resistance can be written as:
Where R = resistance, l = length, A = area of cross-section and ρ = resistivity
CALCULATION:
Given that:
L2 = L1/2
So L1/L2 = 2
As we know that the resistance of the wire is,
When the wire is melted and its length halved then its diameter will increase automatically. But the volume of the wire will be the same.
∴ The volume of original wire = volume of new wire
⇒ A1L1 = A2L2
⇒ A1/A2 = L2/L1 = 1/2
The resistance of the wire in 1st case:
The resistance of the wire in 2nd case