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 chemistry energy fuel cell fuel cells electrochemistry, rechargeable batteries, and fuel cells

Which one of the following cells can convert chemical energy of $O _{2}$ and $H _{2}$ directly into electrical energy:

  1. mercury cell

  2. danicell cell

  3. fuel cell

  4. lead storage cell
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In hydrogen- oxygen fuel cell, the hydrogen is fuel and oxygen is the oxidizing agent. In this cell, the energy of combustion of hydrogen is converted into electrical energy.
Hence, option C is correct.

Multiple choice chemistry energy fuel cell fuel cells electrochemistry, rechargeable batteries, and fuel cells

Which of the following is an example of simple fuel cell?

  1. Lead storage battery

  2. Leclanche cell
  3. $H _2 O _2$

  4. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A fuel cell makes electricity using the energy released by mixing fuel with air, a reaction which creates water and sometimes also carbon dioxide. The most common fuel for fuel cells is hydrogen, which when reacted with oxygen from air produces only water.
$H _{ 2 }O _{2}$ is simple fuel cell which generates electricity by reduction of $H _{ 2 }$ & $O _{ 2 }$.   

Multiple choice chemistry energy fuel cell fuel cells electrochemistry, rechargeable batteries, and fuel cells

An examples of a simple fuel cell is:

  1. lead storage battery
  2. $H _{2} - O _{2}$ cell

  3. daniell cell

  4. lechlanche cell
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$\rightarrow$ The galvanic cells in which the energy of combustion of fuels is directly converted into electrical energy are called fuel cells.
$\rightarrow$ The common example of fuel cell is hydrogen-oxygen fuel cell. Fuel cells are different from ordinary galvanic cells.

Multiple choice chemistry energy fuel cell fuel cells electrochemistry, rechargeable batteries, and fuel cells

In _________ cells, reactants are continuously supplied energy which can be withdrawn indefinately until outside supply of reactant is maintained. These cells are more efficient than conventional batteries and moreover, these are eco-friendly. 

  1. fuel

  2. galvanic

  3. primary

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

Fuel cell is a device that generates electricity by chemical reaction. Every fuel cell has one positive and one negative electrode called anode and cathode respectively. The reactions that produce electricity take place at electrodes.

Multiple choice electrical cells patterns and properties of metals chemistry

The apparatus in which electrical energy is converted into chemical energy is known as:

  1. voltameter

  2. coulometer

  3. both (A) and (B)

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The apparatus in which electrical energy is converted into chemical energy is known as voltameter or coulometer.
Ag or Cu voltameters or coulemeters are used to measure the total charge passed through solution in terms of mass of Ag or Cu deposited there on voltameter or coulometer cathode.

Multiple choice electrical cells patterns and properties of metals chemistry

Electrochemical cells are also called:

  1. electrolytic cells

  2. galvanic cells

  3. fuel cells

  4. voltaic cells
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
Explanation

Electrochemical cell which convert electrical energy into chemical energy is called as electrolytic cell. 
Electrochemical cell which converts chemical energy into electrical energy is called as Galvanic or Voltaic cell

Multiple choice physics heat engine: second law of thermodynamics conversion of heat into work: heat engine and it's efficiency engines and cycles heat engines refrigerators and heat pumps

In a heat engine, heat energy is converted into mechanical energy. 

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The correct answer is option(A).

In thermodynamics, a heat engine is a system that converts heat or thermal energy—and chemical energy—to mechanical energy, which can then be used to do mechanical work.

Multiple choice physics heat engine: second law of thermodynamics conversion of heat into work: heat engine and it's efficiency engines and cycles heat engines refrigerators and heat pumps

The most efficient engine is?

  1. Petrol

  2. Electric

  3. Steam

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

The electric engine is most efficient. Electric motors are very efficient at converting electricity into work. Physicists throw around abstract numbers like 90%, whereas when discussing combustion engines, they use numbers less than 40%. But you cannot compare the efficiency of converting electricity into motion to the efficiency of converting gasoline into motion.

Multiple choice commercial applications sources of water conservation of natural and energy resources energy conservation and sources importance of the conservation of natural resources reduce, recycle, reuse

The use of CFL can save .......... electricity per year.

  1. 1000 megawatt

  2. 6000 megawatts

  3. 100 megawatt

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Compact fluorescent lamps (CFL) are the bulbs which are generally used to save the electricity. These bulbs use and convert only 1/5$^{th}$ of the electricity into light. There is consumption of less electricity. This helps in reduction of about 6000 megawatts of electricity per year. 

Thus, the correct answer is option B. 

Multiple choice ac and dc ac vs dc electro-magnetism effects of electric current physics

Which of the statements is false?
AC: Alternating current
DC: Direct Current 

  1. AC generation is done by a generator

  2. DC generation is done by electrochemical cells

  3. AC generation can be done by electrochemical cells

  4. None
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Electrochemical cells produce DC.

AC is generated by a generator.