Masses of 3 wires of same metal are in the ratio 1:2:3 and their lengths

⇦

⇨

Masses of 3 wires of same metal are in the ratio 1:2:3 and their lengths are in the ratio 3:2:1. The electric resistances are in the ratio

Options

(a) (1:4:9)
(b) (9:4:1)
(c) (1:2:3)
(d) (27:6:1)

Correct Answer:

(27:6:1)

Explanation:

Mass = volume × density = A.l.d

Ald = m

Resistance R = ρl / A = ρl / (m/ld) = dρ (l²/m)

Now, R₂ / R₁ = (ρd / ρd) )(l₂² / l₁²) (m₁/m₂)

= (2/3)² × (1/2) = 2 / 9

⇒ R₂ = (2 / 9) R₁

Again R₃ / R₁ = (ρd / ρd) )(l₃² / l₁²) (m₁/m₃)

= (1/3)² × (1/3) = 1 / 27

⇒ R₃ = (R₁ / 27)

.·. R₁ : R₂ : R₃ = R₁ : (2/9) R₁ : (R₁/27) = 27 : 6 : 1

Related Questions:

1. The radius of a nucleus of mass number A is directly proportional to
2. Initial pressure and volume of a gas are P and 800cc. If the final volume is 100cc
3. In thermodynamics processes which of the following statements is not true?
4. If the unit of force and length are doubled, then unit of energy will be
5. In a circuit, L,C and R are connected in series with an alternating voltage source

Topics: Current Electricity (136)
Subject: Physics (2479)

---

Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score

18000+ students are using NEETLab to improve their score. What about you?

Solve Previous Year MCQs, Mock Tests, Topicwise Practice Tests, Identify Weak Topics, Formula Flash cards and much more is available in NEETLab Android App to improve your NEET score.

---

Share this page with your friends