All Free Electrical Engineering MCQs with Answers

• A. 1
• B. 1 H/m
• C. 1/4JI
• D. 4n x 10-' H/m

Explanation: Relative permeability is defined as μr = μ/μ0, so vacuum has μ = μ0 and therefore μr = 1.

• A. Mica capacitor
• B. Paper capacitor
• C. Electrolytic capacitor
• D. Ceramic capacitor

Explanation: Single-phase motors commonly use an electrolytic capacitor for the starting circuit because it provides a large capacitance in a compact…

• A. dilute sulphuric acid
• B. concentrated sulphuric acid
• C. NaOH
• D. KOH

Explanation: Alkaline cells use an alkaline hydroxide electrolyte, most commonly potassium hydroxide, KOH.

• A. minimum efficiency
• B. minimum current capacity
• C. low internal resistance
• D. high internal resistance

Explanation: A constant-voltage generator must maintain nearly constant terminal voltage as load current changes.

• A. Temperature of surroundings
• B. Specific gravity of electrolyte
• C. Rate of discharge
• D. All of the above

Explanation: Battery capacity depends on temperature, electrolyte specific gravity, and discharge rate.

• A. charged ions
• B. chemical energy
• C. electrostatic energy
• D. electromagnetic energy

Explanation: A lead-acid battery converts electrical energy into chemical energy during charging and releases it as electrical energy during discharge.

• A. Lithium
• B. Zinc-chloride
• C. Mercury
• D. Carbon-zinc

Explanation: A mercury cell has a nominal voltage of about 1.35 V, lower than the roughly 1.5 V of zinc-chloride and carbon-zinc cells.

• A. buckling of plates
• B. faulty separators
• C. lead particles forming circuit between positive and negative plates
• D. excessive accumulation of sediment
• E. any one of aboveElectricity

Explanation: An internal short circuit can result from buckled plates, defective separators, conductive lead particles, or accumulated sediment…

• A. no
• B. very little
• C. less
• D. more

Explanation: Sulfation increases the battery's internal resistance, so charging current produces greater I²R heating.

• A. 1.0
• B. 1.5
• C. 2.4
• D. 2.9

Explanation: A lead-acid cell falls by about 0.4 V from its fully charged condition to its fully discharged condition.

• A. 0.8
• B. 0.95
• C. 1.1
• D. 1.21

Explanation: The Edison, or nickel-iron, cell uses potassium hydroxide electrolyte with a specific gravity commonly taken as about 1.21.

• A. Pb02
• B. PbSC-4
• C. PbO
• D. Pb

Explanation: During prolonged idling, the sulfuric acid electrolyte reacts with the lead-based active material and forms lead sulfate, PbSO₄.

• A. bakelite
• B. rubber
• C. nickel plated steel
• D. aluminium

Explanation: An Edison cell uses a nickel-plated steel container, which provides mechanical strength and improved resistance to the alkaline…

• A. 8
• B. 12
• C. 16
• D. 24Standardized & Admissions Tests

Explanation: Industrial battery capacity is commonly specified at the 8-hour discharge rate, written as an 8-hour or C8 rating.

• A. colour of electrode
• B. gassing
• C. specific gravity
• D. all above

Explanation: Near full charge, a battery shows electrolyte gassing, a stabilized or increased specific gravity, and characteristic electrode-colour…

• A. Deniell cell
• B. Leclanche cell
• C. Lead-acid cell
• D. Edison cell

Explanation: A dry cell is essentially a Leclanché cell in which the electrolyte is converted into a moist paste, making the cell portable and…

• A. produce gassing
• B. increase the internal resistance of the battery
• C. to corrode the positive plates into lead peroxide thereby weakening them physically
• D. bring about all above changes

Explanation: Overcharging decomposes water and causes gassing, raises internal resistance, and accelerates positive-plate corrosion and weakening.

• A. resistance of electrolyte
• B. electrode resistance
• C. surface contact resistance between electrode and electrolyte
• D. all above

Explanation: Cell internal resistance includes ionic resistance of the electrolyte, resistance of the electrodes, and contact or polarization…

• A. Capacity of cell will reduce
• B. Sulphation of plates will occur
• C. Internal resistance will increase
• D. All above will occur

Explanation: Deeply discharging a lead-acid cell promotes sulphation, reducing usable capacity and increasing internal resistance.

• A. low sp. gravity electrolyte
• B. abnormal high temperature
• C. reduced gassing on charge
• D. all above

Explanation: A short circuit rapidly discharges the cell, lowers electrolyte specific gravity, and produces abnormal heating.