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 the essence of change different forms of energy energy conversions energy transformations and energy transfers

An electric heater is used by us to convert electrical energy to:

  1. heat energy

  2. light energy

  3. both a and b

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

An electric heater is used to obtain heat energy. For light energy a bulb or other light sources are used.
An electric heater is used to convert electrical energy to heat energy.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

The correct sequence of energy changes in hydroelectric power station is:

  1. Kinetic to potential to mechanical to electrical

  2. Potential to kinetic to mechanical to electrical

  3. Potential to electrical to mechanical

  4. Potential to electrical to kinetic to mechanical
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

First of all moving water is stored against a dam and then it is allowed to fall on turbine and then as turbine rotates it will produce electricity.

So sequence of energy conversion is 
Kinetic to potential to mechanical to electrical.
Hence option A is best possible.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

Electric heater converts :

  1. electric energy into chemical energy

  2. chemical energy into electric energy

  3. heat energy into electric energy

  4. electric energy into heat energy
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An electric heater is an electrical device that converts electric current to heat. The heating element inside every electric heater is an electrical resistor, and works on the principle of Joule heating: an electric current passing through a resistor will convert that electrical energy into heat energy.

Multiple choice physics electric current and its effects thermal effect of electric current heating effect of electric current effect of electric current

When electric current is flown through a conductor, some amount of:

  1. electrical energy is converted into heat energy.

  2. electrical energy is converted into mechanical energy.

  3. mechanical energy is converted into. electrical energy.

  4. heat energy is converted into electrical energy.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A conductor has its own resistance. Due to the flowing current, certain heat is produced in the conductor according to the Joule's heating effect  i.e   $H = I^2Rt$.

Thus electrical energy is converted into heat energy when a current flows through the conductor.

Multiple choice physics electric current and its effects thermal effect of electric current heating effect of electric current effect of electric current

Which of the following will produce maximum wastage of electricity ?

  1. CFL

  2. Electric bulb

  3. LED lights

  4. All are power savers
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Electric bulb works by heating up a small wire called a filament. Electric current heats the filament so much that it glow. In fact, $90\%$ of the electricity used by a electric bulb is converted to heat and this conversion will produce maximum wastage of electricity.

Multiple choice physics electric current and its effects thermal effect of electric current heating effect of electric current effect of electric current

Appliances based on heating effect of current work on

  1. only A.C.

  2. only D.C.

  3. both A.C. and D.C.

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

As  heat produced depends upon resistance which has no relation with AC or DC but heat produced  also depends upon current as $H \propto\  I^2$ so for heating effect both A.C. and D.C. can be used, that's why appliances based on heating effect can work on AC as well as DC. hence correct option is C.

Multiple choice physics effects of electric current thermal effect of electric current heating effect of electric current electric current and its effects

When we pay for our electricity bill, we are paying for the:

  1. charge used.

  2. current used.

  3. power used.

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

Electricity bill is measured in units where 1 unit is equal to kWh which is the unit of energy. Hence, when we pay for our electricity bill, we pay for the amount of electrical energy consumed by us.

Multiple choice physics electric current and circuit thermal effect of electric current heating effect of electric current electric current and its effects

An electric fan is switched on in a closed room. The air in the room is 

  1. cooled

  2. heated

  3. maintains its temperature

  4. heated or cooled depending on the atmosphere
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If an electric fan is switched on in a closed room, the air will be heated because due to motion of the fan, the speed of air molecules will increase. In fact, we feel cold due to evaporation of our sweat

Multiple choice physics electrical circuits domestic electric circuits and safety precautions domestic and commercial circuit electric power

The electrical appliances in a house are connected in :

  1. series

  2. parallel

  3. either in series or parallel

  4. both in series and parallel
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A parallel connection is preferred in a household circuit.
The main advantages of the parallel system are that the supply can be tapped at any convenient point in the house; moreover each appliance is operated by a separate fuse. If the fuse blows off, only that appliance is to be checked. This system involves less wiring and is cheaper to set up.

Multiple choice physics electrical circuits domestic electric circuits and safety precautions domestic and commercial circuit electric power

Mark the incorrect statement.

  1. In our homes, we receive supply of electric power through a main supply

  2. Red insulation cover, is called live wire

  3. The earth wire, has insulation of green colour

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

In our homes, we receive supply of electric power through a main supply (also called mains), either supported through overhead electric poles or by underground cables. One of the wires in this supply, usually with red insulation cover, is called live wire (or positive). Another wire, with 
black insulation, is called neutral wire (or negative). In our country, the 
potential difference between the two is $220   V$. At the metre-board in the house, these wires pass into an electricity meter through a main fuse. Through the main switch they are connected to the line wires in the house. These wires supply electricity to separate circuits within the house. Often, two separate circuits are used, one of $15   A$ current rating for appliances with higher power ratings such as geysers, air coolers, etc. The other circuit is of 5 A current rating for bulbs, fans, etc. The earth wire, which has insulation of green colour, is usually connected to a metal plate deep in the earth near the house. This is used as a safety measure, especially for those appliances that have a metallic body, for example, electric press, toaster, table fan, refrigerator, etc. The metallic body is connected to the earth wire, which provides a low-resistance conducting path for the current. Thus, it ensures that any leakage of current to the metallic body of the appliance keeps its potential to that of the earth, and the user may not get a severe electric shock.

Multiple choice physics electrical circuits domestic electric circuits and safety precautions domestic and commercial circuit electric power

Each electrical appliance is provided with a _______ core flexible cable. Fill in the blank.

  1. 3

  2. 2

  3. 1

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

Each electrical appliance is provided with three (3) core flexible cables. The insulation on the three wires is of different colours i.e  Brown for live wire, blue for neutral wire and green or yellow for earth wire.