Electricity MCQs – Current, Voltage, Resistance & Circuits
Practice 10 MCQs on electricity fundamentals — Ohm’s Law, series/parallel circuits, electric power, current, resistance, and circuit calculations. Essential for board exams.
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Q1
Ohm’s Law states that V = IR. If V = 12 V and R = 4 Ω, what is the current I?
✓ A – 3 A
I = V/R = 12/4 = 3 A. Ohm’s Law: V = IR, where V is voltage (volts), I is current (amperes), and R is resistance (ohms). Rearrange to find any variable.
I = V/R = 12/4 = 3 A. Ohm’s Law: V = IR, where V is voltage (volts), I is current (amperes), and R is resistance (ohms). Rearrange to find any variable.
Q2
The SI unit of electrical resistance is:
✓ C – Ohm
The SI unit of resistance is the Ohm (Ω), named after Georg Simon Ohm. 1 Ω = 1 V/A. Resistance opposes the flow of electric current in a conductor.
The SI unit of resistance is the Ohm (Ω), named after Georg Simon Ohm. 1 Ω = 1 V/A. Resistance opposes the flow of electric current in a conductor.
Q3
In a series circuit, the total resistance is:
✓ C – The sum of all resistors
In series: R_total = R₁ + R₂ + R₃ + … The same current flows through each resistor. Total resistance always increases when resistors are added in series.
In series: R_total = R₁ + R₂ + R₃ + … The same current flows through each resistor. Total resistance always increases when resistors are added in series.
Q4
In a parallel circuit, the voltage across each branch is:
✓ B – The same
In a parallel circuit, all branches have the same voltage across them — equal to the source voltage. However, the current is divided among branches inversely proportional to their resistance.
In a parallel circuit, all branches have the same voltage across them — equal to the source voltage. However, the current is divided among branches inversely proportional to their resistance.
Q5
Electric power is given by the formula:
✓ C – P = VI
Electric Power P = VI (watts). Also expressed as P = I²R or P = V²/R. Power represents the rate at which electrical energy is converted to another form (heat, light, etc.).
Electric Power P = VI (watts). Also expressed as P = I²R or P = V²/R. Power represents the rate at which electrical energy is converted to another form (heat, light, etc.).
Q6
A current of 2 A flows through a 5 Ω resistor. What is the power dissipated?
✓ B – 20 W
P = I²R = (2)² × 5 = 4 × 5 = 20 W. This formula is useful when you know current and resistance. Alternatively P = VI = V × 2, and V = IR = 2×5 = 10 V, so P = 10×2 = 20 W.
P = I²R = (2)² × 5 = 4 × 5 = 20 W. This formula is useful when you know current and resistance. Alternatively P = VI = V × 2, and V = IR = 2×5 = 10 V, so P = 10×2 = 20 W.
Q7
Which device converts electrical energy into mechanical energy?
✓ C – Electric motor
An electric motor converts electrical energy into mechanical (kinetic) energy. A generator does the opposite — converts mechanical energy into electrical energy. Transformers change voltage levels.
An electric motor converts electrical energy into mechanical (kinetic) energy. A generator does the opposite — converts mechanical energy into electrical energy. Transformers change voltage levels.
Q8
What is the effect of doubling the voltage in a circuit (resistance constant)?
✓ B – Current doubles
From Ohm’s Law: I = V/R. If V doubles and R is constant, I also doubles. This direct proportionality is fundamental to circuit analysis.
From Ohm’s Law: I = V/R. If V doubles and R is constant, I also doubles. This direct proportionality is fundamental to circuit analysis.
Q9
The instrument used to measure electric current is called:
✓ B – Ammeter
An ammeter measures electric current in amperes. It is connected in series in a circuit. A voltmeter (in parallel) measures voltage. A galvanometer detects small currents.
An ammeter measures electric current in amperes. It is connected in series in a circuit. A voltmeter (in parallel) measures voltage. A galvanometer detects small currents.
Q10
Two resistors of 6 Ω and 3 Ω are connected in parallel. What is the equivalent resistance?
✓ B – 2 Ω
1/R = 1/6 + 1/3 = 1/6 + 2/6 = 3/6 = 1/2 → R = 2 Ω. In parallel, equivalent resistance is always less than the smallest individual resistance. Formula: 1/R_eq = 1/R₁ + 1/R₂ + …
1/R = 1/6 + 1/3 = 1/6 + 2/6 = 3/6 = 1/2 → R = 2 Ω. In parallel, equivalent resistance is always less than the smallest individual resistance. Formula: 1/R_eq = 1/R₁ + 1/R₂ + …
About These Electricity MCQs
These Electricity MCQs cover Ohm’s Law, series and parallel circuits, electric power, and key instruments. They are ideal for Class 9 & 10 Physics and FSc entry tests.
Electricity is one of the highest-weightage topics in physics board exams and MDCAT. Mastering Ohm’s Law and circuit calculations is essential.
Topics Covered
- Ohm’s Law — V = IR calculations
- Series circuits — total resistance
- Parallel circuits — equivalent resistance
- Electric power — P = VI, P = I²R
- Ammeter and voltmeter usage
- Energy conversion devices (motors, generators)
Numerical Practice Tips
Always write down V, I, and R values first, then choose the correct formula. For parallel circuits, use 1/R_eq = 1/R₁ + 1/R₂. Practice at least 5 numerical MCQs per session to build speed and accuracy.
Frequently Asked Questions
What is Ohm’s Law? ›
Ohm’s Law states that voltage (V) = current (I) × resistance (R), provided temperature and other physical conditions remain constant. It applies to ohmic (linear) conductors.
What is the difference between series and parallel circuits? ›
In series: same current flows through all components, voltages add up, total resistance increases. In parallel: same voltage across all branches, currents add up, total resistance decreases.
What is electric power? ›
Electric power is the rate of electrical energy transfer. P = VI = I²R = V²/R. The unit is watts (W). 1 kWh = 3.6 × 10⁶ J.
How does an ammeter differ from a voltmeter? ›
An ammeter measures current (connected in series, low resistance). A voltmeter measures voltage (connected in parallel, high resistance). Never connect an ammeter in parallel.
Are these electricity MCQs good for MDCAT? ›
Yes. Electricity fundamentals including Ohm’s Law and circuit analysis are tested in MDCAT Physics. These MCQs cover all core concepts with full explanations.
