Home
Class 12
PHYSICS
Two copper wires have their masses in th...

Two copper wires have their masses in the ratio `2:3` and the lengths in the ratio `3:4` The ratio of their resistances of

A

`4:9`

B

`27:32`

C

`16:9`

D

`27:128`

Text Solution

Verified by Experts

The correct Answer is:
B
The resistance of one wire
`R_=p l_1/A_1`
and the resistance of second wire
`R_2=p l_2/A_2`
Ratio of their resistances
`R_1/R_2=l_1/A_ 1times A_2/l_2`
`because`= mass= density `times` volume
`because` mass= density `times` area `times` height
or `R_1/R_2=(l_1/l_2)^2 times (pA_2l_2)/(pA_ 1 times l_1)`
or `R_1/R_2=(l_1/l_2)^2 times m_2/m_1`
or `R_1/R_2=9/16 times 3/2`
or `R_1/R_2=27/32`
`R_1:R_2=27:32`
Promotional Banner

Similar Questions

Explore conceptually related problems

Three copper wires have their lengths in the ratio 5:3:1 and their masses are in the ratio 1:3:5 . Their electrical resistance will be in the ratio.

Two wires have their lengths in the ratio 1:3 and radius in the ratio 2:1 . What will be the ratio of elongations for the same linear stress?

The base radii of two cylinders are in the ratio 2: 3 and their heights are in the ratio 5: 4 . i) What is the ratio of their volumes? ii) The volume of the first cylinder is 720 centimetres. What is the volume of the second?

Two masses are in the ratio 1:5 . What is the ratio of inertia of this case?

Divide a line of length 7cm in the ratio 3:2