Question

A rheostat has 100 turns of wire of radius 0.4 radius

Answer 1

Dear Student,

◆ Complete question -

Q. A rheostat has 100 turns of a wire of radius 0.4 mm having resistivity 4.2×10^-7ohm metre. The diameter of each turn is 3 cm. What is the maximum value of resistance that it can introduce?

● Answer -

R = 7.876 ohm

● Explanation -

Total length of wire is calculated by -

l = n × 2πR

l = 100 × 2 × 3.142 × 1.5×10^-2

l = 9.426 m

Cross sectional area of wire is -

A = πr^2

A = 3.142 × (0.4×10^-3)^2

A = 5.026×10^-7 m^2

Maximum value of resistance is given by -

R = ρl/A

R = 4.2×10^-7 × 9.426 / 5.026×10^-7

R = 7.876 ohm

Hence, the maximum value of resistance that the wire can introduce is 7.876 ohm.

Thanks dear. Hope this helps you...

Answer 2

Explanation:

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