Question

The resistance of a conductor is 4 ohms. What will be its new resistance
if length of conductor is doubled and area of cross section is halved?
plz solve this numerical ​

Answer 1

Answer:

16 ohm

Explanation:

According to the given question,

Initial

• Let initial, Resistance = R

• Length = L

• Area of cross section = A

And we are asked to find the new resistance if length is doubled and area is halved.

Final

• Let new resistance = R'

• Length = L' = 2L

• Area of cross section = A' = A/2

So we know that resistivity of the given conductor is same.

And we also know that , R = pL/A

Where p = resistivity ( which is constant here)

L = length of the wire

A = Area of cross section

R = Resistance

Therefore,

• R'/R = L' × A/ L × A'

(Resistivity is same , so it gets cancel out)

• R'/R = 2L × A/ L × (A/2)

• R'/R = 4 L×A/L×A

• R'/R = 4

• R' = 4R

By putting the value of R = 4 ohm.

• R' = 4×4

• R' = 16 ohm ans.