Question

(a) A copper wire has diameter 0.5 mm and resistivity of 1.6 × 10-8Q
m. What will be the length of this wire to make its resistance 10 2?
How much does the resistance change if the diameter is doubled?​

Answer 1

Ans: Area of cross-section of the wire, A =π (d/2) 2

Diameter= 0.5 mm = 0.0005 m

Resistance, R = 10 Ω

We know that,

R= rho L/A

L=RA/rho

= 10*3.14*(0.0005/2)2   ............(the whole square)

     1.6*10 raised to -8

= 10*3.14*25  = 122*72

       4*1.6

∴ length of the wire = 122.72m

If the diameter of the wire is doubled, new diameter=2×0.5=1mm=0.001m

Let new resistance be Rʹ

R'=rho L/A

  =1.6*10 raised -8 *122.72

       π(1/2*10 raise -3)2............(the whole square)

 =106*10 raise -8*122.72*4

           3.14*10 raise -6

=250.2* 10 raise -2= 2.5Ω

hope it helps!!!

Answer 2

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Here's your answer mate

┗━━━━•❅•°•❈ ↯ •°•❅•━━━━┛

Reflex action✍

The Automatic response of effector to a stimulus is called a reflex action

Examples:

1 withdrawal of hand and touching fire.

2 sneezing coughing or vomiting when nose larynx or pharynx for get irritated by foreign particles.

3 closure of Eyes on seeing the welding light.

✰Hope it helps❢❢

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