JEE Physics · 140 questions. Try each one, then check the answer and solution.
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Q21.AI-generated practiceSingle-correct MCQEasy
A copper wire is 10 m long and has a cross-sectional area of 1 mm2. The resistivity of copper is 1.7 × 10-8 Ω m. Its resistance is:
Q22.AI-generated practiceSingle-correct MCQEasy
A wire of resistance R is stretched uniformly to twice its length. Its new resistance is:
Q23.AI-generated practiceSingle-correct MCQMedium
A wire of resistance R is stretched uniformly until its radius becomes half of its original value. The new resistance is:
Q24.AI-generated practiceSingle-correct MCQMedium
A wire has a resistance of 10 Ω at 20 °C. The temperature coefficient of resistance of its material is 4 × 10-3 °C-1. Its resistance at 70 °C is:
Q25.AI-generated practiceSingle-correct MCQMedium
The resistivity of a metallic wire depends on:
Q26.AI-generated practiceSingle-correct MCQEasy
A carbon resistor has colour bands brown, black, red and gold, in that order. Its resistance is:
Q27.AI-generated practiceSingle-correct MCQHard
Two wires A and B are made of the same metal. A is twice as long as B and has half the diameter of B. The ratio of their resistances RA : RB is:
Q28.AI-generated practiceSingle-correct MCQMedium
Which of the following does NOT obey Ohm's law?
Q29.AI-generated practiceSingle-correct MCQMedium
When the temperature of a pure semiconductor such as silicon is increased, its resistivity:
Q30.AI-generated practiceSingle-correct MCQHard
A uniform wire of resistance 16 Ω is bent into a circle. The resistance between two diametrically opposite points of the circle is:
Q31.AI-generated practiceSingle-correct MCQMedium
A conductor has conductivity 5 × 107 S/m. The current density in it when the electric field is 0.02 V/m is:
Q32.AI-generated practiceSingle-correct MCQEasy
The SI unit of resistivity is:
Q33.AI-generated practiceSingle-correct MCQHard
A coil has a resistance of 50 Ω at 20 °C and 60 Ω at 70 °C. The temperature coefficient of resistance of its material (with respect to 20 °C) is:
Q34.AI-generated practiceSingle-correct MCQMedium
Alloys such as manganin and constantan are used to make standard resistors mainly because they have:
Q35.AI-generated practiceNumerical valueEasy
A wire 2 m long with cross-sectional area 0.5 mm2 is made of a material of resistivity 5 × 10-7 Ω m. Find its resistance in ohm.
Q36.AI-generated practiceNumerical valueMedium
A wire of resistance 10 Ω is drawn out uniformly to three times its original length. Find its new resistance in ohm.
Q37.AI-generated practiceNumerical valueMedium
A tungsten filament has a resistance of 20 Ω at 20 °C. Taking its temperature coefficient of resistance as 4.5 × 10-3 °C-1 (constant), find its resistance in ohm at 2020 °C.
Q38.AI-generated practiceNumerical valueHard
A uniform wire of resistance 12 Ω is bent into the shape of a square. Find the resistance (in ohm) between two diagonally opposite corners of the square.
Q39.AI-generated practiceAssertion–ReasonEasy
Assertion (A): The resistance of a metallic wire increases with temperature. Reason (R): The relaxation time of free electrons decreases with temperature because collisions with the vibrating ions become more frequent.
Q40.AI-generated practiceAssertion–ReasonMedium
Assertion (A): When a wire is stretched to twice its length, its resistance becomes four times. Reason (R): The resistivity of the material increases on stretching.