Science General ยท Physics

Energy and Electrical Devices

1,193 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

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.

Multiple choice

The energy stored in a watch spring is ______.

  1. kinetic energy

  2. potential energy

  3. heat energy

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

A watch spring stores energy as potential energy when it is wound up. As the spring unwinds, this stored potential energy is converted into kinetic energy that drives the watch mechanism. This is a classic example of elastic potential energy in mechanical systems.

Multiple choice

Directions: In the following question, four statements are provided between an opening statement 1 and a closing statement 6. The statements are jumbled up and form a coherent paragraph when properly arranged. Select the alternative representing the proper and logical sequencing of these six taken together.

  1. Machines can be divided into four groups: mechanical, electrical, fluid power, and prime movers.

A. Common examples of prime movers include waterwheels, windmills and nuclear energy plants.

B. They also convert energy in moving fluids to mechanical energy, as fluid motors, hydraulic cylinders, and turbines.

C. Prime movers convert natural forms of energy, such as those found in streams and winds, into mechanical energy.

D. Fluid-power machines convert mechanical energy to energy in moving fluids, as in compressors and hydraulic pumps.

  1. Similarly, electric machines convert mechanical to electrical energy as in generators and alternators and convert electrical to mechanical energy in electrical motors and loudspeakers.

  1. BDAC

  2. CADB

  3. BACD

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

As one can easily infer that sentence C describes the conversion of various forms of energy by prime movers, therefore, as in sentence A, example of prime movers has been given, it follows sentence C. In sentence 6, an analogy of electric machines converting two different forms of energy have been given. This therefore, needs some example preceding it. Therefore, DB should precede sentence 6. This sequence is presented in option (2), hence the answer.

Multiple choice

__________ converts electrical energy into mechanical energy.

  1. Coil

  2. Motor

  3. Conductor

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

A generator converts mechanical energy into electrical energy, while a motor does the opposite, it converts electrical energy into mechanical energy. Both devices work on electromagnetic induction, i.e. emf is induced in the coil by a changing magnetic field.

Multiple choice

The mechanical device which transfers chemical energy of fuel into mechanical energy in the form of motion is called

  1. rolling stock

  2. railway

  3. wagon

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

A locomotive is the primary power vehicle in a rail transport system that converts the chemical energy stored in fuel (through combustion) into mechanical energy to produce motion. Unlike rolling stock, wagons, or the railway infrastructure itself, the locomotive contains the engine that performs this energy conversion.

Multiple choice

Which among the following minimises the energy consumption and maximises the picture brightness?

  1. A black layer

  2. A cold cathode

  3. The control grid

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

A black layer is a coat on the filament of the indirectly heated hot cathode in a cathode ray tube, intended to optimise the output of electrons from the cathode, thus minimising the energy consumption and heat generated while maximising the picture brightness.

Multiple choice

The hydrogen-absorbing alloy is used by

  1. alkaline battery

  2. nickel-cadmium battery

  3. lithium-ion battery

  4. nickel-metal hydride cell
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A nickel-metal hydride cell is a type of rechargeable battery similar to the nickel-cadmium cell. The NiMH battery uses a hydrogen-absorbing alloy for the negative electrode instead of cadmium.

Multiple choice

The battery capable of acting as water activated batteries is

  1. The penny battery

  2. A deep-cycle battery

  3. An earth battery

  4. A reserve battery
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An earth battery is a pair of electrodes made of two dissimilar metals, such as iron and copper, which are buried in the soil or immersed in the sea. Earth batteries act as water activated batteries and if the plates are sufficiently far apart, they can tap telluric currents.