?a wire is stretched 30% what is the percentage change in resistance

The percentage change in resistance of the wire is 69%.

Explanation:

Resistance of a wire can be determined by,

R = (ρl) ÷ A

Where R is its resistance, l is the length of the wire, A its cross sectional area and ρ its resistivity.

When the wire is stretched, its length and area changes but its volume and resistivity remains constant.

= 1.3l, and =

So that;

= (ρ) ÷ = (ρ × 1.3l) ÷ ()

    = (1.3lρ) ÷ ()

    = × [(ρl) ÷ A]

   = 1.69R               (∵ R = (ρl) ÷ A)

= 1.69R

Where is the new resistance, is the new length, and is the new area after stretching the wire.

The change in resistance of the wire = - R

                                      = 1.69R  - 1R

                                      = 0.69R

The percentage change in resistance = × 100

                                                               = 0.69 × 100

                                                              = 69%

The percentage change in resistance of the wire is 69%.

when insulating materials rub against each other, they may become electrically charged . electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. the material that gains electrons becomes negatively charged. the material that loses electrons is left with a positive charge.

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