Question

The thickness of two wires are 6×10^-6 and 1.5×10^-7. Find the ratio of the thickness of two wires.​

Answer 1

Answer:

Correct option is

D

3:2

The resistance R is given by:

R=

A

ρl

=

πr

2

ρl

So,

R

2

R

1

=

(

πr

2

2

ρ

2

l

2

)

(

πr

1

2

ρ

1

l

1

)

R

2

R

1

=

ρ

2

l

2

r

1

2

ρ

1

l

1

r

2

2

But

ρ

2

ρ

1

=

1

2

,

l

2

l

1

=

3

1

,

r

2

r

1

=

3

2

⇒

R

2

R

1

=

1

2

×

3

1

×(

2

3

)

2

=

2

3