Class 10 Electric Motor – Working Principle (Easy Explanation)
Class 10 Electric Motor working principle with easy explanation.
Although CBSE has removed this topic from the Class 10 chapter Magnetic Effects of Electric Current, the Electric Motor remains one of the most important applications of electromagnetism. It is essential for higher classes, especially Class 12 Physics, where motors, generators, and electromagnetic induction form core concepts.
This article provides a clear, simple, and exam-oriented
understanding of the working principle of an electric motor, its
construction, application, and related important questions.
What is an Electric Motor?
An electric motor is a device that converts electrical
energy into mechanical energy. It works on the principle that a
current-carrying conductor placed in a magnetic field experiences a force.
This force produces rotation, allowing motors to run
fans, mixers, washing machines, pumps, and industrial machines.
Working Principle of Electric Motor (Easy Explanation)
The electric motor works on Fleming's Left-Hand Rule,
which states:
When a current-carrying conductor is placed in a magnetic
fie
ld, it experiences a force perpendicular to both the current and the
magnetic field.
This force causes the coil inside the motor to rotate.
Key Idea
- Current
→ creates magnetic effect
- Magnetic
field → interacts with current
- Interaction
→ produces force
- Force
→ rotates the coil
- Continuous
rotation → mechanical work
Construction of Electric Motor (Simple Points)
1. Armature (Coil)
- A
rectangular coil made of insulated copper wire.
- Represented
as ABCD in most diagrams.
- Carries
current, experiences force.
2. Magnetic Field
- Provided
by a pair of permanent magnets or electromagnets.
- Creates
a uniform magnetic field between the poles.
3. Split-Ring Commutator
- A
device that reverses current direction every half rotation.
- Ensures
continuous rotation in the same direction.
- Made
of two copper halves.
4. Brushes
- Carbon
brushes that press against the commutator.
- Provide
current to the rotating coil.
5. Power Source
- Battery,
DC source or cell.
How an Electric Motor Works (Step-by-Step)
Step 1: Current flows through the coil
Electricity enters the coil ABCD via the brushes and
commutator.
Step 2: Magnetic Force acts on the coil
- Side
AB experiences force downwards.
- Side
CD experiences force upwards.
This happens due to the interaction of magnetic field and
electric current.
Step 3: Coil begins to rotate
Because forces on AB and CD are in opposite directions, the
coil rotates.
Step 4: Split Ring reverses current
When the coil reaches vertical position:
- Commutator
reverses current direction.
- The
forces remain in the same direction as before.
- Coil
continues rotating in the same direction.
Step 5: Motor keeps running
This repeated reversal ensures continuous rotation, allowing the motor to do work.
Why Electric Motor is still important for Class 10 students?
Even though CBSE removed this from the Class 10 syllabus:
- Foundation
for Class 12 Physics
- Required
for Electromagnetic Induction, Motors, and Alternators.
- Useful
in competitive exams
- NTSE,
KVPY (Class 11–12 level), Olympiads, JEE fundamentals.
- Daily-Life
Relevance
- Fans,
mixers, sewing machines, toys, pumps, elevators – all use motors.
- Understanding
Technology Around Us
- Electric
vehicles, robotics, automation rely heavily on motors.
Types of Electric Motors (Basic Idea for Class 10)
1. DC Motor
- Uses
direct current
- Works
on split-ring commutator
- Taught
in Class 10 earlier
2. AC Motor (for higher classes)
- Uses
alternating current
- Works
on electromagnetic induction
Important Questions (MCQs, Very Short, Short, Long, Case-Based)
Note - The Following Questions are not the part of CBSE Class 10 Syllabus of 2025-26, however it is useful in self assessment and may CBSE can ask Case Based Question on Electric Motor.
MCQs (Board Pattern)
Q1. Electric motor works on the principle of:
a) Electromagnetic induction
b) Electric heating
c) Magnetism of current
d) Fleming’s Left Hand Rule
Correct Answer: d) Fleming’s Left-Hand Rule
Q2. The device that reverses current in the motor is:
a) Brush
b) Armature
c) Commutator
d) Rotor
Correct Answer: c) Commutator
Q3. Force on a current-carrying conductor in magnetic
field depends on:
a) Current only
b) Magnetic field only
c) Both current and magnetic field
d) Voltage
Correct Answer: c) Both current and magnetic field
Very Short Answer Questions (10–20 words)
Q1. What energy change takes place in an electric
motor?
Ans: Electrical energy converts into mechanical energy.
Q2. Which rule determines direction of force?
Ans: Fleming’s Left-Hand Rule.
Q3. Name the part responsible for current reversal.
Ans: Split-ring commutator.
Short Answer Questions (40–60 words)
Q1. State Fleming’s Left-Hand Rule.
Ans: According to the rule, if the first finger, second finger and thumb
of the left hand are placed mutually perpendicular, the first finger shows
magnetic field, second finger shows current, and thumb shows direction of force
on the conductor.
Q2. What is the function of carbon brushes in a
motor?
Ans: Carbon brushes press against the split-ring commutator and help
transfer current from the external circuit to the rotating armature coil
without preventing its motion.
Long Answer Questions (80–120 words)
Q1. Describe the working of an electric motor with a
diagram.
Answer:
An electric motor works on the principle that a current-carrying conductor
placed in a magnetic field experiences a force. The motor consists of a
rectangular coil placed between the poles of a magnet. When current flows
through the coil, opposite forces act on the two sides, causing rotation. As
the coil completes half-turn, the commutator reverses current direction,
ensuring that the forces on the two sides remain in the direction of rotation.
This results in continuous rotation. Brushes keep supplying current to the
coil. This converts electrical energy into mechanical energy.
Case-Based / Competency Questions
Case Study:
A student observed that when a current flows through a coil placed in a
magnetic field, the coil rotates. He also notices that rotation becomes
smoother when a commutator is used with carbon brushes.
Q1. Why does the coil rotate?
Ans: Magnetic force acts on the current-carrying coil.
Q2. Why is commutator necessary?
Ans: It reverses current every half rotation, maintaining direction of
rotation.
Q3. Why are carbon brushes used?
Ans: They allow smooth transfer of current to the rotating coil.
Summary
The electric motor is an important application of
electromagnetism and a foundation concept for higher studies. It works on the
principle of force on a current-carrying conductor placed in a magnetic field.
Key components include armature, magnets, split-ring commutator, and brushes.
Understanding this concept helps students in later classes, practical
applications, and competitive exams.
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