If a certain piece of copper is to be shaped into a conductor of minimum resistance, its length (L) and cross-sectional area A shall be respectively
(A) L/3 and 4 A
(B) L/2 and 2 A
(C) 2L and A2
(D) L and A
1 Answers
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The wire of length L and resistance R is stretched so that its radius of cross-section is halved. What is its new resistance?
Correct answer is (D) 16R
2 Answers 1 views
DC current flows in a metal piece of non uniform cross-section. Which of these quantities remains constant along the conductor
Drift velocity and current density will change as it depends upon area of cross-section whereas current will remain constant.
2 Answers 2 views
A force of 1 N doubles the length of a cord having cross-sectional area 1 mm^2. The Young’s modulus of the material of cord is
Correct option is: (C) 106 N m-2
2 Answers 1 views
The increase in energy of a metal bar of length ‘L’ and cross-sectional area ‘A’ when compressed with a load ‘M’ along its length is
(B) \(\frac{F^2 L}{2AY}\) U = \(\frac{1}{2}\) × F × l = \(\frac{1}{2}\) × F × \(\frac{FL}{AY}=\frac{F^2 L}{2AY}\)
2 Answers 1 views
Two rods of same material are equal in length, but one has cross-sectional area double the other.
Correct option is: (C) both rods will expand equally.
2 Answers 1 views
The resistance of a conductor …………………. when the length of a conductor increased for providing constant temperature and cross-sectional area.
B) increases
2 Answers 1 views
When the length of a wire is doubled, its resistance for same cross-sectional area
Correct option is D) doubled
2 Answers 1 views
If the length and diameter of a conductor both are halved, the resistance of the conductor becomes …………………….
Correct option is D) halved
2 Answers 1 views
A piece of platinum wire has resistance of 2.5 Ω at 0 °C. If its temperature coefficient of resistance is 4 × 10^-3/°C. Find the resistance
Given: R0 = 2.5 Ω α = 4 × 10-3/°C = 0.004/°C T = 80 °C To find: Resistance at 80 °C (RT) Formula: RT = R0(l + αT) Calculation: From formula, RT = 2.5 [1+ (0.004 × 80)] =...
2 Answers 3 views
Two wires are made of the same material and have the same volume. However, wire 1 has cross-sectional area `A` and wire 2 has cross-sectional area `3A
Correct Answer - 9 9
2 Answers 1 views