Science General ยท 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

Which of the following is a device for storing electric charge?

  1. Capacitor

  2. Counter

  3. Compass

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

A capacitor is an electronic component designed specifically to store electric charge in an electric field. A counter measures radiation events, a compass shows direction, and a cyclotron accelerates particles.

Multiple choice

We are facing an energy crisis because

  1. energy cannot be created

  2. energy cannot be destroyed

  3. energy changes from useful to useless form

  4. energy changes from useless to useful form
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If energy changes from useful to useless form, then energy crisis occurs. Hence, option (3) is correct.

Multiple choice

Directions: Choose the correct answer from the options given below:

Which among is the device which converts the mechanical energy into electrical energy?

  1. DVD

  2. Sphygmomanometer

  3. Ammeter

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

A dynamo is an electrical generator that converts mechanical energy (rotational motion) into electrical energy through electromagnetic induction. Ammeters measure current, sphygmomanometers measure blood pressure, and DVDs are optical storage media. The dynamo's principle is fundamental to power generation.

Multiple choice

What does dynamo convert?

  1. It converts mechanical energy to electrical energy

  2. It converts light energy to electrical energy

  3. It converts mechanical energy to light energy

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A dynamo is an electrical generator that converts mechanical energy (motion) into electrical energy using electromagnetic induction. When a coil rotates in a magnetic field, it produces an electric current. Option B describes solar panels, and option C is not what dynamos do.

Multiple choice

________ is used to cool the machines in automobiles.

  1. Radiator

  2. Radar

  3. Lactometer

  4. Ammeter

  5. none
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A radiator is a heat exchanger that transfers thermal energy from hot coolant to the air. It circulates engine coolant through a series of tubes and fins, allowing heat to dissipate. This prevents the engine from overheating during operation.

Multiple choice

The device that converts mechanical energy into electrical energy is

  1. motor

  2. invertor

  3. generator

  4. all of the above

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A generator converts mechanical energy into electrical energy through electromagnetic induction. When a conductor (wire coil) is rotated within a magnetic field, it induces an electric current. This principle, discovered by Faraday, is the foundation of all electrical power generation.

Multiple choice

Electro magnetic induction phenomenon is used in ______.

  1. storage cell

  2. dry cell

  3. electric tester

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

Electromagnetic induction, discovered by Michael Faraday, is the principle behind electric generators. When a conductor moves through a magnetic field, it induces an electromotive force. Storage cells and dry cells store chemical energy, while testers measure electrical properties but don't generate it.

Multiple choice

Which of the following energy is converted to electrical energy in a cell

  1. mechanical energy

  2. chemical energy

  3. solar energy

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

Cells (batteries) convert chemical energy stored in their electrodes and electrolyte into electrical energy through redox reactions. The chemical reactions at the anode and cathode release electrons that flow through the external circuit as electric current. Mechanical, solar, and potential energy are converted to electricity by other devices, not cells.