Science General · Physics

Energy and Electrical Devices

1,182 Questions

Energy and electrical devices focus on energy conversion, household electrical appliances, batteries, and electric vehicle technology. These principles are essential components of general science syllabi across major competitive examinations. Review these practice questions to strengthen understanding of electrical energy applications and devices.

Energy conversionHousehold electrical appliancesBatteries and cellsElectric vehicles

Energy and Electrical Devices Questions

Multiple choice physics magnetism and electromagnetism electric generator ac generator magnetic effects of electric current

A dynamo converts

  1. mechanical energy into sound energy

  2. mechanical energy into electrical energy

  3. electrical energy into mechanical energy

  4. electrical energy into sound energy
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Dynamo is an electric generator where shaft is rotated mechanically and electric energy is produced. It converts the mechanical motion of the driven shaft into electrical motion,with the aid of a magnet.

Multiple choice physics magnetism and electromagnetism electric generator ac generator magnetic effects of electric current

Starter is used in

  1. high power electric motors

  2. low power electric motors

  3. transformers

  4. galvanometer
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A starter (also self starter, self, or starter motor) is an electric motor, pneumatic motor, hydraulic motor, an internal-combustion engine in case of very large engines or other device used for rotating an internal-combustion engine so as to initiate the engine's operation under its own power.

Multiple choice physics magnetism and electromagnetism electric generator ac generator magnetic effects of electric current

To convert mechanical energy into electrical energy, one can use

  1. $DC$ dynamo
  2. $AC$ dynomo

  3. motor

  4. transformer
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

A dynamo converts mechanical energy to electrical energy, producing a DC current, using a commutator.
A motor converts various type of energy like fossil fuel, steam an electrical energy to mechanical energy.
A transformer magnetically couples different electrical circuits. 

Multiple choice physics effects of electric current electric generator ac generator magnetic effects of electric current

Which instrument works on the principle of "Electromagnetic induction?

  1. Electric motor

  2. Fuse

  3. Electric bell

  4. Electric generator
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An electric generator converts mechanical energy into electrical energy based on Faraday's law of electromagnetic induction. An electric motor works on the force exerted on a current-carrying conductor in a magnetic field, while a fuse and bell operate on thermal and magnetic effects respectively.

Multiple choice physics effects of electric current electric generator ac generator magnetic effects of electric current

What energy conversion takes place in a generator ?

  1. mechanical energy into magnetic energy.

  2. mechanical energy into chemical energy.

  3. mechanical energy into electric energy.

  4. electrical energy into mechanical energy.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Answer is C.

The generation of electrical power requires relative motion between a magnetic field and a conductor. In a generator, mechanical energy is converted into electrical energy. The electricity produced by most generators is in the form of alternating current. In general, AC generators, motors and other electrical equipment are simpler, cheaper and more reliable than their DC counterparts.  AC electricity can be easily transformed into higher or lower voltages making it more versatile than DC electricity. 
Multiple choice physics effects of electric current electric generator ac generator magnetic effects of electric current

Complete the sentence by using the correct words given in the brackets:

A ________ (generator / transformer/motor/transducer) is a source of electricity that generates large amount of electricity in a power house.

  1. Motor

  2. Generator

  3. Transducer

  4. Transformer
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A generator is a device that converts mechanical energy into electrical energy. It is the source of electricity used to generate large amounts of electricity in power house.

Multiple choice physics magnetism and electromagnetism electric generator ac generator magnetic effects of electric current

A dynamo 

  1. Creates mechanical energy

  2. Creates electrical energy

  3. Converts electrical energy into mechanical energy

  4. Converts mechanical energy into electrical energy
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Generally a small dynamo require a permanent magnet. Using the Faraday's law of induction, rotating a coil of wire and magnetic fields to convert mechanical rotation into a direct electric current. Thus, a dynamo converts mechanical energy to electrical energy.  

Multiple choice physics magnetism and electromagnetism electric generator ac generator magnetic effects of electric current

Dynamo converts :

  1. electric energy into magnetic energy

  2. magnetic energy into potential energy

  3. mechanical energy into electrical energy

  4. no energy
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
The electric dynamo uses rotating coils of wire and magnetic fields to convert mechanical rotation into a pulsing direct electric current through Faraday's Law of induction (electromagnetic induction).
Multiple choice physics magnetism and electromagnetism electric generator ac generator magnetic effects of electric current

The device which converts the mechanical energy in to electric energy is

  1. D.C. motor

  2. A.C. dynamo

  3. Transformer

  4. Starter
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The AC dynamo (generator) is made up of stationary magnets (stator) which create a powerful magnetic field, and a rotating magnet (rotor) which distorts and cuts through the magnetic lines of flux of the stator. When the rotor cuts through lines of magnetic flux it makes electricity. Thus mechanical energy is converted into electrical energy. 

Multiple choice physics magnetism and electromagnetism electric generator ac generator magnetic effects of electric current

For a dynamo which one of the following statements is correct

  1. It converts electrical energy into light energy

  2. It converts kinetic energy into heat energy

  3. It converts mechanical energy into electrical energy

  4. It converts electrical energy into mechanical energy
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A  dynamo converts mechanical energy into electrical energy according to Faraday's Law of Electromagnetic Induction.


Answer-(C).