Question

Find the resistance of a circular coil of 500 turns, the radius of each of them is 7.5 cm. If the radius of the wire itself is 0.01mm, its Resistivity is 2x10^-8 ohm.m.

Answer 1

u hv to use formula
R=rho*L/A

Answer 2

r = radius, L = length, A = area? I only have the radius of each turn, the radius of the wire and resistivity. What is h and o?

Can yo please explain more?

Answer 3

i mean rho=resistivity

Answer 4

Aha, how can I get L and A then?

Answer 5

ok

Answer 6

wts the circumference of a circlr of wire

Answer 7

The radius of each turn is 7.5cm, there are 500 turns. Also the radius of the wire is 0.01mm, I'm not sure what to do with the radius of the wire. But I'm guessing I can get the circumference with \[2*\pi*r\]

Answer 8

ya u r right
here r=7.5cm

Answer 9

u r going to find out the circumference of circle

Answer 10

n radius of that circle is r=7.5cm

Answer 11

bt need to convert the unit frm cm to meter

Answer 12

right?

Answer 13

right and then?

Answer 14

can u find out the cross sectional area of ur given wire

Answer 15

i mean
A=?

Answer 16

My problem is that I don't know what to do with 2 radii.

To find A I guess we will use
\[\pi*r ^{2}\]

Answer 17

ya ur guess is almost correct

Answer 18

for calculating cross sectional area
A=π*r^2
here u hv to use r=0.01mm

Answer 19

because 0.01mm is the radius of wire not circle

Answer 20

right?

Answer 21

but u hv to convert the unit frm mm to meter

Answer 22

I'm not sure when to use the radius 7.5cm and when to use 0.01mm

Answer 23

when u r going to calculate the circumference of ur given circle of wire, u hv to use the radius of that circle n its bigger
r=7.5cm

Answer 24

anyway if u feel confused then we can talk over skype, if u want

Answer 25

Thanks to you I managed to solve it!