CURRENT ELECTRICITY
1. Electric current is defined as:
a) The flow of protons
b) The flow of electrons
c) The flow of neutrons
d) The flow of photons
2. Which equation represents the relationship between electric current, charge, and time?
a) P = IV
b) R = V/I
c) I = Q/t
d) V = IR
3. The SI unit of electric current is:
a) Ampere (A)
b) Volt (V)
c) Ohm (Ω)
d) Coulomb (C)
4. The direction of conventional current flow is:
a) From positive to negative
b) From negative to positive
c) From high potential to low potential
d) It depends on the type of material
5. Which property of a material opposes the flow of electric current?
a) Conductivity
b) Resistance
c) Capacitance
d) Inductance
6. Electric resistance is measured in:
a) Coulombs (C)
b) Amperes (A)
c) Volts (V)
d) Ohms (Ω)
7. Ohm's law states that the current passing through a conductor is directly proportional to:
a) The resistance of the conductor
b) The voltage across the conductor
c) The temperature of the conductor
d) The length of the conductor
8. Which of the following materials has the highest electrical conductivity?
a) Rubber
b) Glass
c) Copper
d) Plastic
9. The resistance of a conductor depends on:
a) Its length and voltage
b) Its temperature and current
c) Its diameter and charge
d) Its mass and velocity
10. The unit of resistivity is:
a) Ohm (Ω)
b) Volt (V)
c) Ampere (A)
d) Ohm-meter (Ω·m)
11. The resistivity of a material depends on:
a) Its temperature
b) Its length
c) Its cross-sectional area
d) Its color
12. The temperature coefficient of resistivity represents the change in resistance of a material with respect to:
a) Voltage
b) Temperature
c) Length
d) Current
13. When resistivity increases with temperature, the material is classified as:
a) Superconductor
b) Insulator
c) Conductor
d) Semiconductor
14. Two resistors are connected in parallel. The equivalent resistance is:
a) The sum of their resistances
b) The reciprocal of the sum of their resistances
c) The product of their resistances
d) The average of their resistances
15. Two resistors are connected in series. The equivalent resistance is:
a) The sum of their resistances
b) The reciprocal of the sum of their resistances
c) The product of their resistances
d) The average of their resistances
16. The total resistance of n identical resistors connected in parallel is:
a) R/n
b) R × n
c) n/R
d) nR
17. The total resistance of n identical resistors connected in series is:
a) R/n
b) R × n
c) n/R
d) nR
18. Power dissipation in a resistor can be calculated using the formula:
a) P = IV
b) P = I²R
c) P = V²/R
d) P = R/I
19. Which of the following factors affects the power dissipation in a resistor?
a) Voltage across the resistor
b) Current passing through the resistor
c) Resistance value of the resistor
d) All of the above
20. The unit of power is:
a) Ampere (A)
b) Volt (V)
c) Ohm (Ω)
d) Watt (W)
21. What is the formula for power in terms of voltage and current?
a) P = IV
b) P = I²R
c) P = V²/R
d) P = R/I
22. Which device converts chemical energy into electrical energy?
a) Capacitor
b) Diode
c) Resistor
d) Battery
23. The electromotive force (emf) of a battery represents:
a) The voltage across the battery
b) The current passing through the battery
c) The potential difference between the terminals of the battery
d) The energy supplied by the battery per unit charge
24. The SI unit of electromotive force is:
a) Ampere (A)
b) Volt (V)
c) Ohm (Ω)
d) Joule (J)
25. A battery with an emf of 12V is connected to a resistor of 3Ω. What is the current passing through the resistor?
a) 4A
b) 9A
c) 12A
d) 36A
26. In a circuit, the sum of the emfs is equal to:
a) The sum of the currents
b) The sum of the resistances
c) The sum of the voltages
d) The sum of the powers
27. Which of the following statements about electric circuits is true?
a) Current flows only in closed circuits
b) Current flows only in open circuits
c) Current flows in both open and closed circuits
d) Current does not flow in any circuit
28. What is the current flowing through a 10Ω resistor connected to a 24V power supply?
a) 0.4A
b) 2.4A
c) 14A
d) 34A
29. What happens to the resistance of a conductor when its temperature increases?
a) It decreases
b) It increases
c) It remains constant
d) It becomes zero
30. A wire has a resistance of 10Ω at 25°C. What will be its resistance at 75°C if its temperature coefficient of resistivity is 0.004/°C?
a) 10.2Ω
b) 10.4Ω
c) 10.8Ω
d) 11.2Ω
31. When a wire is stretched, its resistance:
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero
32. Which of the following materials has the highest resistivity?
a) Silver
b) Copper
c) Aluminum
d) Tungsten
33. What is the resistance of a wire with a resistivity of 2Ω·m and a length of 4m?
a) 0.5Ω
b) 2Ω
c) 8Ω
d) 16Ω
34. Which of the following materials is an insulator?
a) Aluminum
b) Glass
c) Copper
d) Silver
35. Which type of circuit has only one path for current flow?
a) Series circuit
b) Parallel circuit
c) Combination circuit
d) Open circuit
36. A circuit is said to be open when:
a) The current is flowing
b) The circuit is disconnected
c) The voltage is zero
d) The resistance is infinite
37. When a resistor is added in series to a circuit, the total resistance:
a) Decreases
b) Increases
c) Remains the same
d) Depends on the values of other resistors
38. When resistors are connected in series, their total resistance is:
a) Equal to the sum of their individual resistances
b) Less than the sum of their individual resistances
c) Greater than the sum of their individual resistances
d) Independent of the values of the resistors
39. Which type of circuit has multiple paths for current flow?
a) Series circuit
b) Parallel circuit
c) Combination circuit
d) Open circuit
40. The equivalent resistance of two resistors connected in parallel is always:
a) Less than the resistance of either resistor
b) Greater than the resistance of either resistor
c) Equal to the sum of their resistances
d) Equal to the average of their resistances
41. What happens to the voltage across each resistor in a parallel circuit?
a) It increases
b) It decreases
c) It remains the same
d) It depends on the values of the resistors
42. What happens to the current in each resistor in a parallel circuit?
a) It increases
b) It decreases
c) It remains the same
d) It depends on the values of the resistors
43. In a parallel circuit, the total current is equal to:
a) The sum of the currents in each branch
b) The difference between the currents in each branch
c) The average of the currents in each branch
d) The product of the currents in each branch
44. In a parallel circuit, if one branch is open (disconnected), the current in the other branches will:
a) Increase
b) Decrease
c) Remain the same
d) Become zero
45. In a parallel circuit, if one branch has a high resistance compared to the other branches, the majority of the current will flow through the branch with:
a) The highest resistance
b) The lowest resistance
c) An intermediate resistance
d) None of the above
46. In a series circuit, the total voltage is equal to:
a) The sum of the voltages across each component
b) The difference between the voltages across each component
c) The average of the voltages across each component
d) The product of the voltages across each component
47. In a series circuit, the total resistance is equal to:
a) The sum of the resistances of each component
b) The difference between the resistances of each component
c) The average of the resistances of each component
d) The product of the resistances of each component
48. In a series circuit, if one component is open (disconnected), the current in the other components will:
a) Increase
b) Decrease
c) Remain the same
d) Become zero
49. In a series circuit, if one component has a high resistance compared to the other components, the majority of the voltage will drop across the component with:
a) The highest resistance
b) The lowest resistance
c) An intermediate resistance
d) None of the above
50. What is the relationship between power, voltage, and current in a resistor?
a) P = IV
b) P = I²R
c) P = V²/R
d) P = R/I
ANSWER KEY:
1. b) The flow of electrons
2. c) I = Q/t
3. a) Ampere (A)
4. a) From positive to negative
5. b) Resistance
6. d) Ohms (Ω)
7. b) The voltage across the conductor
8. c) Copper
9. b) Its temperature and current
10. d) Ohm-meter (Ω·m)
11. a) Its temperature
12. b) Temperature
13. b) Insulator
14. b) The reciprocal of the sum of their resistances
15. a) The sum of their resistances
16. c) n/R
17. d) nR
18. b) P = I²R
19. d) All of the above
20. d) Watt (W)
21. a) P = IV
22. d) Battery
23. d) The energy supplied by the battery per unit charge
24. b) Volt (V)
25. a) 4A
26. c) The sum of the voltages
27. a) Current flows only in closed circuits
28. b) 2.4A
29. b) It increases
30. c) 10.8Ω
31. a) Increases
32. d) Tungsten
33. c) 8Ω
34. b) Glass
35. a) Series circuit
36. b) The circuit is disconnected
37. b) Increases
38. a) Equal to the sum of their individual resistances
39. b) Parallel circuit
40. a) Less than the resistance of either resistor
41. c) It remains the same
42. c) It remains the same
43. a) The sum of the currents in each branch
44. d) Become zero
45. b) The lowest resistance
46. a) The sum of the voltages across each component
47. a) The sum of the resistances of each component
48. d) Become zero
49. a) The highest resistance
50. b) P = I²R
