NEET UG - Electrical resistivity and conductivity, series and parallel combinations of resistors, temperature dependence of resistance Online Test (MCQ Quiz)

1. What is electrical resistivity?

A) The opposition to the flow of electric current offered by a material. B) The ease with which electric current flows through a material. C) The ratio of electric field to current density in a material. D) The total resistance of a circuit.

2. Which of the following units is used to measure electrical resistivity?

A) Ohm-meter (Ω·m) B) Siemens per meter (S/m) C) Ampere per meter (A/m) D) Volt per meter (V/m)

3. Electrical conductivity is the reciprocal of which property?

A) Resistivity B) Resistance C) Reactance D) Inductance

4. A material with high electrical resistivity will have:

A) Low electrical conductivity B) High electrical conductivity C) Zero electrical conductivity D) Infinite electrical conductivity

5. Which of the following is a good electrical conductor?

A) Rubber B) Glass C) Copper D) Wood

6. Which of the following is a good electrical insulator?

A) Silver B) Aluminum C) Plastic D) Gold

7. The resistance of a wire is directly proportional to its:

A) Length B) Cross-sectional area C) Resistivity D) Both length and resistivity

8. The resistance of a wire is inversely proportional to its:

A) Length B) Cross-sectional area C) Resistivity D) Temperature

9. If the length of a wire is doubled, its resistance will:

A) Remain the same B) Be halved C) Be doubled D) Be quadrupled

10. If the cross-sectional area of a wire is doubled, its resistance will:

A) Remain the same B) Be halved C) Be doubled D) Be quadrupled

11. For a given material, resistance is independent of:

A) Length B) Cross-sectional area C) Temperature D) Shape

12. When resistors are connected in series, the total resistance is:

A) The sum of individual resistances B) The reciprocal of the sum of reciprocals of individual resistances C) The average of individual resistances D) Zero

13. When resistors are connected in parallel, the total resistance is:

A) The sum of individual resistances B) The reciprocal of the sum of reciprocals of individual resistances C) The average of individual resistances D) Infinite

14. In a series combination of resistors, the current through each resistor is:

A) Different B) The same C) Zero D) Dependent on the voltage source

15. In a parallel combination of resistors, the voltage across each resistor is:

A) Different B) The same C) Zero D) Dependent on the resistance value

16. If two resistors R1 and R2 are connected in series, the equivalent resistance Req is:

A) Req = R1 + R2 B) 1/Req = 1/R1 + 1/R2 C) Req = (R1 * R2) / (R1 + R2) D) Req = R1 - R2

17. If two resistors R1 and R2 are connected in parallel, the equivalent resistance Req is:

A) Req = R1 + R2 B) 1/Req = 1/R1 + 1/R2 C) Req = (R1 * R2) / (R1 + R2) D) Req = R1 / R2

18. What happens to the resistance of most metallic conductors when their temperature increases?

A) It decreases B) It increases C) It remains unchanged D) It becomes zero

19. The temperature dependence of resistance for metals is generally described by:

A) A linear relationship B) An exponential relationship C) A logarithmic relationship D) No relationship

20. The formula for the resistance at temperature T, R(T), for a metal is often given by R(T) = R0(1 + α(T - T0)), where α is the:

A) Resistivity B) Conductivity C) Temperature coefficient of resistance D) Specific heat capacity

21. For most metals, the temperature coefficient of resistance (α) is:

A) Positive B) Negative C) Zero D) Variable

22. Semiconductors like silicon and germanium typically have a temperature coefficient of resistance that is:

A) Positive B) Negative C) Zero D) Alternating

23. Which material has a very low temperature coefficient of resistance, making it suitable for precision resistors?

A) Copper B) Aluminum C) Manganin D) Iron

24. The resistance of a semiconductor generally:

A) Increases with increasing temperature B) Decreases with increasing temperature C) Remains constant with temperature changes D) Becomes infinite at high temperatures

25. If three resistors of 2 Ω, 3 Ω, and 5 Ω are connected in series, what is the total resistance?

A) 1 Ω B) 10 Ω C) 30 Ω D) 0.968 Ω

26. If three resistors of 2 Ω, 3 Ω, and 5 Ω are connected in parallel, what is the total resistance?

A) 1 Ω B) 10 Ω C) 30 Ω D) 0.968 Ω

27. Consider two resistors, R1 = 10 Ω and R2 = 20 Ω. If they are connected in parallel, the equivalent resistance is:

A) 10 Ω B) 20 Ω C) 6.67 Ω D) 30 Ω

28. Consider two resistors, R1 = 10 Ω and R2 = 20 Ω. If they are connected in series, the equivalent resistance is:

A) 10 Ω B) 20 Ω C) 6.67 Ω D) 30 Ω

29. The SI unit of electrical conductivity is:

A) Ohm B) Siemens C) Siemens per meter D) Ohm-meter

30. Resistivity of a material is an intrinsic property. Which of the following factors does NOT affect resistivity?

A) Material type B) Temperature C) Dimensions of the sample D) Presence of impurities

31. A wire of resistance R is stretched to double its length. The new resistance will be:

A) R B) 2R C) 4R D) R/2

32. A wire of resistance R is cut into two equal halves. If these halves are connected in parallel, the equivalent resistance will be:

A) R B) 2R C) R/2 D) R/4

33. Which of the following has the highest resistivity at room temperature?

A) Silver B) Copper C) Aluminum D) Glass

34. Which of the following has the lowest resistivity at room temperature?

A) Iron B) Tungsten C) Silver D) Gold

35. In a parallel circuit, if one of the resistors is removed, the total resistance will:

A) Increase B) Decrease C) Remain the same D) Become infinite

36. In a series circuit, if one of the resistors is removed (and the circuit is reconnected), the total resistance will:

A) Increase B) Decrease C) Remain the same D) Become zero

37. The relationship between conductivity (σ) and resistivity (ρ) is:

A) σ = ρ B) σ = 1/ρ C) ρ = 1/σ D) σ = -ρ

38. What does the temperature coefficient of resistance represent?

A) The change in resistance per degree Celsius change in temperature. B) The ratio of resistance to temperature. C) The total resistance at a specific temperature. D) The rate of change of resistivity with temperature.

39. Which statement is true about the temperature dependence of resistance for semiconductors?

A) Resistance increases significantly with temperature. B) Resistance decreases significantly with temperature. C) Resistance is independent of temperature. D) Resistance remains constant above a certain temperature.

40. A Nichrome wire is used in electric heaters because it has:

A) Low resistivity and positive temperature coefficient B) High resistivity and positive temperature coefficient C) Low resistivity and negative temperature coefficient D) High resistivity and negative temperature coefficient

41. If a resistor of 100 Ω has a temperature coefficient of 0.004 /°C, what is its resistance at 100°C if its resistance at 0°C is 100 Ω?

A) 100 Ω B) 140 Ω C) 40 Ω D) 104 Ω

42. What is the primary reason for the increase in resistance of metals with temperature?

A) Increased number of free electrons B) Increased vibration of the lattice atoms C) Decreased collision frequency of electrons D) Change in the material's density

43. A circuit contains three resistors in parallel: 10 Ω, 20 Ω, and 30 Ω. If a 6V battery is connected across them, what is the current through the 10 Ω resistor?

A) 0.6 A B) 0.3 A C) 0.2 A D) 1.1 A

44. A circuit contains three resistors in series: 10 Ω, 20 Ω, and 30 Ω. If a 6V battery is connected across them, what is the current through the 20 Ω resistor?

A) 0.1 A B) 0.2 A C) 0.6 A D) 0.3 A

45. The resistivity of a material is independent of:

A) The nature of the material B) Temperature C) The dimensions of the conductor D) The number of free electrons per unit volume

46. If the temperature of a conductor increases, its conductivity:

A) Increases B) Decreases C) Remains constant D) Becomes zero

47. A wire has resistance R. If it is melted and recast into a wire of half its length, the new resistance will be:

A) R/4 B) R/2 C) 2R D) 4R

48. What is the equivalent resistance of three identical resistors R connected in series?

A) R/3 B) R C) 3R D) 9R

49. What is the equivalent resistance of three identical resistors R connected in parallel?

A) R/3 B) R C) 3R D) 9R

50. The relation R = ρL/A defines resistance (R) in terms of resistivity (ρ), length (L), and cross-sectional area (A). If ρ is constant and L is doubled, what must happen to A to keep R constant?

A) A must be halved B) A must be doubled C) A must be quadrupled D) A must remain unchanged

Electrical resistivity and conductivity, series and parallel combinations of resistors, temperature dependence of resistance - Online Test

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