Chapter 9: Electric Current — Online MCQ Test
PHYSICAL SCIENCES · CLASS 10th · Telangana State Board
Practice Chapter 9: Electric Current with a free chapter-wise online MCQ test.
This chapter covers: This chapter examines electrodynamics defining electric current potential difference and electromotive force (EMF). Students master Ohm's Law ($V = IR$) analyze factors affecting r....
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Chapter 9: Electric Current — Important Questions & Answers
Electric current is defined as the rate of flow of _____ through a conductor.
- A. electrons
- B. electric charge
- C. ions
- D. protons
Answer: B. electric charge
Electric current is defined as the amount of electric charge flowing per unit time through a cross-section of a conductor, measured in amperes (coulombs per second).
Electric current is defined as the amount of electric charge flowing per unit time through a cross-section of a conductor, measured in amperes (coulombs per second).
The SI unit of electric current is:
- A. Coulomb
- B. Volt
- C. Ampere
- D. Ohm
Answer: C. Ampere
The ampere (A) is the SI unit of electric current, defined as one coulomb of charge flowing per second through a conductor.
The ampere (A) is the SI unit of electric current, defined as one coulomb of charge flowing per second through a conductor.
The resistance of a conductor depends on which of the following factors?
- A. Length of the conductor only
- B. Cross-sectional area only
- C. Material and temperature of the conductor only
- D. Length, cross-sectional area, material, and temperature of the conductor
Answer: D. Length, cross-sectional area, material, and temperature of the conductor
Resistance is given by R = ρL/A, where ρ (resistivity) depends on the material and temperature, L is length, and A is cross-sectional area, showing dependence on all these factors.
Resistance is given by R = ρL/A, where ρ (resistivity) depends on the material and temperature, L is length, and A is cross-sectional area, showing dependence on all these factors.
The electromotive force (EMF) of a cell differs from the potential difference across its terminals because:
- A. EMF is always greater than terminal voltage due to internal resistance
- B. EMF measures the total work done per unit charge by the chemical reactions
- C. Some energy is lost as heat in the internal resistance of the cell
- D. All of the above
Answer: D. All of the above
EMF represents total work per unit charge from the chemical source, while terminal voltage = EMF - (current × internal resistance), accounting for energy loss in internal resistance.
EMF represents total work per unit charge from the chemical source, while terminal voltage = EMF - (current × internal resistance), accounting for energy loss in internal resistance.
A conductor with resistivity ρ = 1.7 × 10⁻⁸ Ωm, length 2m, and cross-sectional area 1mm² has a resistance of approximately:
- A. 0.034Ω
- B. 34Ω
- C. 3.4Ω
- D. 0.0034Ω
Answer: B. 34Ω
Using R = ρL/A = (1.7 × 10⁻⁸ × 2)/(1 × 10⁻⁶) = (3.4 × 10⁻⁸)/(10⁻⁶) = 34Ω, where area must be converted to m² (1mm² = 10⁻⁶ m²).
Using R = ρL/A = (1.7 × 10⁻⁸ × 2)/(1 × 10⁻⁶) = (3.4 × 10⁻⁸)/(10⁻⁶) = 34Ω, where area must be converted to m² (1mm² = 10⁻⁶ m²).