# How to make powerful alarm using a dc motor

## INTRODUCTION

In this topic, we are going to show you how to build a powerful alarm with a dc motor with information for your science project or exhibitions.

DC motor is a device which is helpful in converting direct current into mechanical work.

## DC motor Working Principle

Lorentz Law states that the current carrying conductor, when placed in a magnetic and also electric field, will experience a force and the dc motor is designed based on this principle.

This force which is created is known as the Lorentz force. The direction of force is depicted by Flemming left-hand rule.

This rule states that when thumb finger, middle finger and index finger of the left hand are displaced from each other by 90 degrees then middle finger represents the direction of the magnetic field.

Thumb finger represents the direction of forces acting on the conductor whereas the index finger represents the direction of flow of current.

## Powerful alarm using dc motor Information or theory

DC motor is mainly constructed with two main parts namely armature and stator.

The stator is a stationary part while the armature is rotating the part and armature coil, in turn, is connected to DC supply.

Brushes and commutators are parts of the armature coil. A commutator helps in converting AC induces in the armature into DC while brushes transmit current from rotating part of the motor to a stationary external load.

The armature is placed in between the south and the North Pole of a permanent magnet.

When DC power is supplied to armature coil then current will start to flow through it and develops its own field around the coil.

Fields produced by both coil and magnet interact and the resultant field develops across the conductor.

This field creates a force at ends of conductor and hence the coil starts rotating.

## Uses of powerful alarm using dc motor

It can be used to alert the people like theft in bank or any important places by ringing the bell or alarm

## Step by step to make powerful alarm using a dc motor

In this video, we will show you the following steps and items that can be used to build powerful alarm with dc motor model at home by taking help freely from your parents.

## Materials Used to make powerful alarm using a dc motor

• White and Color Chart Paper
• Card Board box
• Battery
• Motor
• Wires
• Steel vessel glass
• Hot Glue gun
• Screw

## Questions & Answers on powerful alarm using a dc motor

1. What is the working principle of the DC motor?
DC motor works on the principle of Lorentz Law.
2. What is the advantage of a DC motor?
The advantage of the DC motor is that it can develop constant torque over a wide speed application.
3. Why are DC motors used??
DC motors are quick starters, reversing, variable speeds with voltage input, and high starting torque and finally they are cheaper to control than AC.
4. Are AC motors better than DC?
No, DC motors are better than AC due to the secondary magnetic field that is being generated from permanent magnets in comparison to copper windings.
5. What are the types of DC motor?
Types of DC motors are Permanent Magnet DC Motors, Series DC Motors, Shunt DC Motors, and Compound DC Motors.

## Conclusions

In this project, we learn on the concept of working of DC motor,powerful alarm explanation and information