Question

Two wires A and B of equal masses and of the same metal are taken. The diameter of
Two wires A and B of ea
wire A is half the diameter of the wire B. If the resistance of wire A be 24 ohm, the
resistance of B will be
(d) 6.0 ohm
(a) 3 ohm
(b) 1.5 ohm
(c) 4.5ohm
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Answer 1

Answer:

Explanation:You just need to apply the formula of resistance here, which is

R = resistivity× length of the wire/ ara of cross section of wire

Since, both the wires are made of same metal, their resistivity will be same.

Resistance of wire A, RA = 24 OHM =pL/A

p = resistivity

L = length of wire

A = area of cross section of wire

= πd²/4

RA = 4pL/πd²

half the diameter of the wire B is equal of that of A.

D/2 = d

D = 2d

So RB = 4pL/πD² = 4pL/4πd² = (1/4)(4pL/πd²)

RB = RA/4 = 24/4 = 6 OHM

pls mark it

Answer 2

Since the masses of both wires is same hence they will have same density.

• Now since They same mass and also same density hence they have equal volumes as well

Now A1 x L1 = A2 x L2

since

diameter of 1st wire = 1/2 diameter of second wire

hence area of first wire = 1/4 the are of second hence length of 1st wire = 4lenght if second wire

since R is directly proportional to L/A

hence R2 will be 1/16 times of R1

R2 = 1/16 x 24 = 1.5 ohm