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PHY 114 > Chpt 4 Current Electricity > Flashcards

Chpt 4 Current Electricity Flashcards

1
Q

QUESTION

A

OPTION 1

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2
Q
  1. What is the unit of resistivity? (A) Ohm-meter (Ω·m) (B) Ohm (C) Volt (D) Ampere
A

Answer: A) Ohm-meter (Ω·m)

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3
Q
  1. Which material has the lowest resistivity according to the text? (A) Silver (B) Copper (C) Tungsten (D) Aluminum
A

Answer: A) Silver

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4
Q
  1. What is the reciprocal of resistivity called? (A) Conductivity (B) Resistance (C) Voltage (D) Power
A

Answer: A) Conductivity

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5
Q
  1. In the formula, what does represent? (A) Temperature coefficient of resistivity (B) Resistivitya reference temperature (C) Potential difference (D) Length of the material
A

Answer: B) Resistivity at a reference temperature

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6
Q
  1. The resistance of a wire depends on its: (A) Length and cross-sectional area (B) Material only (C) Voltage applied (D) Electric field
A

Answer: A) Length and cross-sectional area

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7
Q
  1. Which material has a temperature coefficient of resistivity that is negative? (A) Carbon (B) Silver (C) Tungsten (D) Aluminum
A

Answer: A) Carbon

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8
Q
  1. What is the critical temperature for mercury’s superconductivity? (A) 4.2K (B) 20K (C) 77K (D) 300K
A

Answer: A) 4.2K

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9
Q
  1. Which of the following materials exhibits superconductivity? (A) Mercury (B) Copper (C) Iron (D) Silver
A

Answer: A) Mercury

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10
Q
  1. What happens to the resistivity of a semiconductor as temperature increases? (A) It decreases (B) It increases (C) It remains constant (D) It fluctuates
A

Answer: A) It decreases

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11
Q
  1. What type of material is typically used to make thermistors? (A) Semiconductors (B) Metals (C) Insulators (D) Superconductors
A

Answer: A) Semiconductors

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12
Q
  1. What is the temperature coefficient of resistivity for pure metals? (A) Positive (B) Negative (C) Zero (D) Infinite
A

Answer: A) Positive

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13
Q
  1. What is the relationship between resistance and resistivity? (A) Resistance = Resistivity × (Length / Area) (B) Resistance = Resistivity × Area (C) Resistance = Resistivity × Length (D) Resistance = Resistivity × Power
A

Answer: A) Resistance = Resistivity × (Length / Area)

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14
Q
  1. Which material has the highest resistivity? (A) Glass (B) Silver (C) Copper (D) Aluminum
A

Answer: A) Glass

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15
Q
  1. What happens to the resistivity of a metal as the temperature increases? (A) It increases (B) It decreases (C) It remains constant (D) It fluctuates randomly
A

Answer: A) It increases

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16
Q
  1. Which of the following materials is used to make standard resistors? (A) Manganin (B) Silver (C) Copper (D) Tungsten
A

Answer: A) Manganin

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17
Q
  1. How is the resistance of a wire affected if its length is tripled, assuming the material is unchanged? (A) It increases by a factor of 3 (B) It decreases by a factor of 3 (C) It stays the same (D) It increases by a factor of 9
A

Answer: A) It increases by a factor of 3

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18
Q
  1. Which material is considered the best conductor of electricity? (A) Silver (B) Copper (C) Tungsten (D) Aluminum
A

Answer: A) Silver

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19
Q
  1. What is the formula for the resistance of a wire based on its resistivity? (A) (B) (C) (D)
A

Answer: A)

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20
Q
  1. What happens to the resistivity of a superconductor below its critical temperature? (A) It drops to zero (B) It increases dramatically (C) It remains constant (D) It decreases gradually
A

Answer: A) It drops to zero

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21
Q
  1. What is the temperature coefficient of resistivity for alloys like manganin? (A) Low (B) High (C) Zero (D) Infinite
A

Answer: A) Low

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22
Q
  1. In the example where a wire is stretched, what happens to its cross-sectional area? (A) It decreases (B) It increases (C) It remains constant (D) It fluctuates
A

Answer: A) It decreases

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23
Q
  1. What is the unit of the temperature coefficient of resistivity? (A) (B) Ohm-meter (C) Ampere (D) Volt-meter
A

Answer: A)

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24
Q
  1. What type of materials exhibit a regular decrease in resistivity as temperature increases? (A) Semiconductors (B) Insulators (C) Metals (D) Superconductors
A

Answer: A) Semiconductors

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25
Q
  1. What is the resistance of a wire at a given temperature related to? (A) Its resistivity at that temperature (B) Its voltage (C) Its current (D) Its power
A

Answer: A) Its resistivity at that temperature

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26
Q
  1. What happens to the current in a superconducting ring? (A) It continues indefinitely without any driving field (B) It gradually decreases (C) It remains constant (D) It stops after a while
A

Answer: A) It continues indefinitely without any driving field

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27
Q
  1. What is the unit of power in a circuit? (A) Watt (J/s) (B) Joule (C) Volt (D) Ampere
A

Answer: A) Watt (J/s)

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28
Q
  1. What does the total energy consumed by an appliance depend on? (A) Power and time (B) Voltage and resistance (C) Resistance and current (D) Current and time
A

Answer: A) Power and time

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29
Q
  1. Which of the following factors influences the resistance of a wire? (A) Length and cross-sectional area (B) Current and power (C) Temperature and voltage (D) Voltage and time
A

Answer: A) Length and cross-sectional area

30
Q
  1. What is the primary use of superconductors? (A) Lossless power transmission (B) To increase resistance in circuits (C) To reduce electric field strength (D) To store energy in high-voltage batteries
A

Answer: A) Lossless power transmission

31
Q
  1. According to Ohm’s law, what is the relationship between voltage and current? (A) Voltage is proportional to current (B) Voltage is inversely proportional to current (C) Voltage equals current divided by resistance (D) Voltage is independent of current
A

Answer: A) Voltage is proportional to current

32
Q
  1. Which of the following materials are Ohmic conductors? (A) Metals (B) Diodes (C) Photocells (D) Transistors
A

Answer: A) Metals

33
Q
  1. What is the reciprocal of resistivity called? (A) Conductivity (B) Resistance (C) Capacitance (D) Impedance
A

Answer: A) Conductivity

34
Q
  1. What is the unit of electrical current? (A) Ampere (B) Volt (C) Watt (D) Ohm
A

Answer: A) Ampere

35
Q
  1. In which type of conductors does the resistance vary with applied voltage? (A) Non-ohmic conductors (B) Ohmic conductors (C) Superconductors (D) Semi-conductors
A

Answer: A) Non-ohmic conductors

36
Q
  1. What is the drift velocity in a copper wire when current flows through it? (A) The velocity at which charge carriers move (B) The speed of the applied voltage (C) The frequency of the alternating current (D) The speed of the electric field
A

Answer: A) The velocity at which charge carriers move

37
Q
  1. What happens to the resistance of a conductor if its length is doubled? (A) It doubles (B) It halves (C) It remains the same (D) It quadruples
A

Answer: A) It doubles

38
Q
  1. What is the term for the reciprocal of resistance? (A) Conductance (B) Power (C) Impedance (D) Voltage
A

Answer: A) Conductance

39
Q
  1. What is the resistance of a 2.6m long conductor with a uniform radius of 0.3cm, given a potential difference of 6V and a current of 0.144A? (A) It depends on resistivity (B) It is 12.5 Ohms (C) It is 2.3 Ohms (D) It is 0.5 Ohms
A

Answer: C) It is 2.3 Ohms

40
Q
  1. What is the formula for calculating power in a circuit? (A) P = IV (B) P = I²R (C) P = V² / R (D) P = QV
A

Answer: A) P = IV

41
Q
  1. What is the heat produced by a heating coil with a resistance of 50Ω for 3 minutes and 20 seconds? (A) 30.0 kJ (B) 25.0 kJ (C) 40.0 kJ (D) 35.0 kJ
A

Answer: A) 30.0 kJ

42
Q
  1. What is the drift velocity of free electrons in a wire when current is 2.04A in a copper wire? (A) 1.25 × 10⁻³ m/s (B) 0.50 × 10⁻³ m/s (C) 1.45 × 10⁻³ m/s (D) 1.35 × 10⁻³ m/s
A

Answer: A) 1.25 × 10⁻³ m/s

43
Q
  1. Which of the following is a feature of superconductors? (A) Zero resistivity below critical temperature (B) High resistance at low temperatures (C) High voltage tolerance (D) Increased current flow without loss
A

Answer: A) Zero resistivity below critical temperature

44
Q
  1. How is the current density in a conductor calculated? (A) j = I / A (B) j = A / I (C) j = I × A (D) j = V / R
A

Answer: A) j = I / A

45
Q
  1. What is the formula for calculating the resistance of a wire? (A) R = ρ(L / A) (B) R = V / I (C) R = I × V (D) R = ρ(A / L)
A

Answer: A) R = ρ(L / A)

46
Q
  1. What is the conductance (in Siemens) of an object that draws 800 mA of current at 12.0V? (A) 0.0667 S (B) 0.0833 S (C) 0.1 S (D) 0.5 S
A

Answer: B) 0.0833 S

47
Q
  1. What is required to sustain the flow of charges through a conductor? (a) A potential difference, (b) A conductor’s length, (c) A thick wire, (d) A neutral atom
A

Answer: (a) A potential difference

48
Q
  1. What produces the electric field inside a conductor? (a) Electric force, (b) Collisions between charges, (c) Resistance of the conductor, (d) Absence of current
A

Answer: (a) Electric force

49
Q
  1. Which of these is not an example of an energy source for maintaining electric current? (a) Electric generator, (b) Battery, (c) Thermometer, (d) Dry cell
A

Answer: (c) Thermometer

50
Q
  1. What happens to molecules of salts, acids, and bases when dissolved in water? (a) They ionize, (b) They solidify, (c) They remain unchanged, (d) They lose electrons permanently
A

Answer: (a) They ionize

51
Q
  1. What was Volta’s contribution to current electricity? (a) He discovered the electric battery, (b) He defined current density, (c) He invented electric circuits, (d) He established Ohm’s law
A

Answer: (a) He discovered the electric battery

52
Q
  1. Which of these symbols represents the positive terminal of a battery? (a) Longer line, (b) Shorter line, (c) Circle, (d) Triangle
A

Answer: (a) Longer line

53
Q
  1. The unit of electric current is: (a) Ampere, (b) Coulomb, (c) Volt, (d) Ohm
A

Answer: (a) Ampere

54
Q
  1. What defines current density? (a) Current per unit area, (b) Voltage per unit charge, (c) Resistance per unit length, (d) Charge per unit time
A

Answer: (a) Current per unit area

55
Q
  1. What determines the direction of conventional current in a conductor? (a) Flow of positive charges, (b) Flow of negative charges, (c) Movement of electrons, (d) Direction of resistance
A

Answer: (a) Flow of positive charges

56
Q
  1. In a conductor, the flow of current is primarily due to: (a) Flow of electrons, (b) Movement of protons, (c) Collision of nuclei, (d) Movement of atoms
A

Answer: (a) Flow of electrons

57
Q
  1. Drift velocity is defined as: (a) Average velocity of charges due to an electric field, (b) Velocity of atoms in a conductor, (c) Speed of light in a wire, (d) Random motion of electrons
A

Answer: (a) Average velocity of charges due to an electric field

58
Q
  1. Current density is directly proportional to: (a) Drift velocity, (b) Wire length, (c) Resistance, (d) Battery size
A

Answer: (a) Drift velocity

59
Q
  1. What property is associated with materials that resist the flow of electric current? (a) Resistivity, (b) Conductivity, (c) Density, (d) Ionization
A

Answer: (a) Resistivity

60
Q
  1. Ohm’s law states that current is directly proportional to: (a) Potential difference, (b) Temperature, (c) Wire length, (d) Cross-sectional area
A

Answer: (a) Potential difference

61
Q
  1. What type of graph represents Ohmic conductors? (a) Straight line through the origin, (b) Curved line, (c) Vertical line, (d) Horizontal line
A

Answer: (a) Straight line through the origin

62
Q
  1. Which of the following is NOT an Ohmic conductor? (a) Junction diode, (b) Copper wire, (c) Carbon resistor, (d) Eureka wire
A

Answer: (a) Junction diode

63
Q
  1. What is the equation for resistance in terms of resistivity? (a) , (b) , (c) , (d)
A

Answer: (a)

64
Q
  1. What happens to resistance if the length of a wire is increased? (a) It increases, (b) It decreases, (c) It remains constant, (d) It becomes zero
A

Answer: (a) It increases

65
Q
  1. What provides greater resistance in a wire? (a) Small cross-sectional area, (b) High conductivity, (c) Large cross-sectional area, (d) Short length
A

Answer: (a) Small cross-sectional area

66
Q
  1. Which characteristic is common to non-Ohmic conductors? (a) Nonlinear I-V characteristics, (b) High drift velocity, (c) Uniform resistance, (d) Straight line graph
A

Answer: (a) Nonlinear I-V characteristics

67
Q
  1. What is the unit of resistivity? (a) Ohm-meter, (b) Coulomb-second, (c) Ampere-meter, (d) Volt-second
A

Answer: (a) Ohm-meter

68
Q
  1. The motion of charges in a wire without an electric field is: (a) Random and nondirectional, (b) Steady and uniform, (c) Constant and forward, (d) Accelerated
A

Answer: (a) Random and nondirectional

69
Q
  1. In which direction do electrons flow in a circuit? (a) Negative to positive terminal, (b) Positive to negative terminal, (c) Randomly, (d) Circularly
A

Answer: (a) Negative to positive terminal

70
Q
  1. Which of the following describes conventional current flow? (a) Positive charges flow from positive to negative terminal, (b) Electrons flow from positive to negative terminal, (c) Current flows in random directions, (d) Atoms flow through the conductor
A

Answer: (a) Positive charges flow from positive to negative terminal

71
Q
  1. What determines the resistance of a material? (a) Resistivity, length, and cross-sectional area, (b) Voltage and current, (c) Drift velocity and charge density, (d) Conductivity and ionization energy
A

Answer: (a) Resistivity, length, and cross-sectional area

PHY 114 (8 decks)

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