Preparing for the TNPSC exam? This TNPSC Physics Energy Test 5 is designed to strengthen your understanding of the Energy topic through important exam-oriented MCQs. Practice this Physics Energy Test to revise key concepts, improve your TNPSC Physics preparation, and boost your confidence before the exam.
TNPSC Physics Energy Test 5 – All Questions Detailed Explanations
TNPSC Physics Energy Test 5 is a comprehensive Physics Energy Test created for final revision of the complete Energy chapter. This grand revision covers work, power, efficiency, mechanical energy, electrical energy, the commercial unit of electricity, renewable and non-renewable energy sources, energy transformations, and the law of conservation of energy. The mixed MCQs follow the latest TNPSC Physics examination pattern, helping aspirants revise important concepts, improve problem-solving skills, and strengthen their overall TNPSC exam preparation with detailed explanations for every question.
1. Electricity consumption in households is measured in:
Answer: C. Kilowatt-hour
Electricity consumed in households is measured in kilowatt-hours (kWh), which is the commercial unit of electrical energy used by electricity boards for billing. One kilowatt-hour represents the energy consumed by a 1000 W appliance operating for one hour.
Quick Revision
• Commercial unit of electrical energy = Kilowatt-hour (kWh)
• SI unit of energy = Joule (J)
• 1 kWh = 3.6 × 10⁶ J
• Electricity bills are calculated based on kilowatt-hours (units) consumed.
Real-Life Example
If a 1000 W electric heater operates for 1 hour, it consumes 1 kWh (1 unit) of electrical energy, which is recorded on the household electricity bill.
2. Which of the following appliances mainly converts electrical energy into mechanical energy?
Answer: A. Electric fan
An electric fan contains an electric motor that converts electrical energy into mechanical energy. The motor rotates the fan blades, producing airflow and cooling the surroundings.
Quick Revision
• Electric motor converts electrical energy into mechanical energy.
• Electric fans operate using an electric motor.
• Mechanical energy is the energy associated with motion.
Real-Life Example
When you switch on a ceiling fan, electricity powers the motor, causing the blades to rotate and circulate air throughout the room.
3. Which source of energy is available continuously, irrespective of day and night?
Answer: C. Geothermal
Geothermal energy is obtained from the Earth’s internal heat. Since this heat is continuously available beneath the Earth’s surface, geothermal energy can be used throughout the day without depending on sunlight or wind.
Quick Revision
• Geothermal energy comes from the Earth’s internal heat.
• It is a renewable source of energy.
• It is available continuously throughout the day.
Real-Life Example
Countries such as Iceland use geothermal energy to generate electricity and provide heating throughout the year.
4. A hydroelectric power station primarily utilizes the energy of:
Answer: A. Flowing water
A hydroelectric power station uses the kinetic energy of flowing or falling water to rotate turbines. The turbines drive generators, which convert mechanical energy into electrical energy.
Quick Revision
• Hydroelectric power uses flowing or falling water.
• Flowing water rotates turbines.
• Generators convert mechanical energy into electrical energy.
Real-Life Example
The Mettur Dam in Tamil Nadu generates electricity by using the energy of flowing water to rotate turbines connected to generators.
5. Which of the following fuels is renewable?
Answer: C. Biogas
Biogas is produced from the decomposition of organic waste such as cattle dung, food waste, and agricultural residues. Since these materials are naturally replenished, biogas is considered a renewable and eco-friendly source of energy.
Quick Revision
• Biogas is produced from organic waste.
• It is a renewable and clean fuel.
• Biogas helps reduce waste and environmental pollution.
Real-Life Example
Many rural households use biogas plants to convert cattle dung into cooking fuel, reducing the use of firewood and LPG.
6. A machine is considered more efficient when it:
Answer: C. Gives maximum useful output
The efficiency of a machine is the ratio of useful output energy to the total input energy. A machine is considered more efficient when it converts a larger portion of the input energy into useful work while minimizing energy loss.
Quick Revision
• Efficiency = (Useful Output Energy ÷ Input Energy) × 100%
• Higher efficiency means less energy is wasted.
• No machine is 100% efficient because some energy is always lost, mainly as heat.
Real-Life Example
An LED bulb is more efficient than a traditional incandescent bulb because it converts more electrical energy into light and less into heat.
7. Which form of energy is stored in water kept at a height?
Answer: B. Potential energy
Water stored at a height possesses gravitational potential energy because of its elevated position. When the water is released, this stored energy is converted into kinetic energy and can be used to generate electricity.
Quick Revision
• Potential energy is the energy possessed due to position.
• Water stored at a height has gravitational potential energy.
• Potential energy can be converted into kinetic and electrical energy.
Real-Life Example
Water stored behind a dam has potential energy, which is converted into electricity when it flows through turbines in a hydroelectric power station.
8. Which of the following is an example of energy transformation?
Answer: A. Electric bulb producing light
Energy transformation is the process of changing energy from one form to another. An electric bulb converts electrical energy into light energy, while a part of the electrical energy is also converted into heat.
Quick Revision
• Energy can be transformed from one form to another.
• Electric bulb: Electrical energy → Light energy + Heat energy.
• Energy is transformed, not created or destroyed.
Real-Life Example
When you switch on a bulb in your home, electrical energy is converted into light that illuminates the room along with a small amount of heat.
9. Which source of energy causes the least air pollution during electricity generation?
Answer: C. Solar
Solar energy generates electricity directly from sunlight without burning fossil fuels. As a result, it produces little to no air pollution during electricity generation and helps reduce greenhouse gas emissions.
Quick Revision
• Solar energy is a renewable energy source.
• It does not require burning fossil fuels.
• It helps reduce air pollution and carbon emissions.
Real-Life Example
Solar panels installed on homes and schools generate clean electricity from sunlight without releasing smoke or harmful gases into the atmosphere.
10. The law of conservation of energy states that energy:
Answer: C. Can only be transformed
The law of conservation of energy states that energy can neither be created nor destroyed. It can only be transformed from one form to another, while the total amount of energy remains constant.
Quick Revision
• Energy cannot be created or destroyed.
• Energy only changes from one form to another.
• Total energy remains constant in an isolated system.
Real-Life Example
When a pendulum swings, its potential energy changes into kinetic energy and back again, while the total mechanical energy remains nearly constant if friction is neglected.
11. Which of the following devices converts mechanical energy into electrical energy?
Answer: A. Generator
A generator converts mechanical energy into electrical energy through the principle of electromagnetic induction. It is widely used in power stations to produce electricity.
Quick Revision
• Generator converts mechanical energy into electrical energy.
• It works on the principle of electromagnetic induction.
• Power plants use generators to produce electricity.
Real-Life Example
In a hydroelectric power station, flowing water rotates a turbine connected to a generator, which produces electricity for homes and industries.
12. The energy possessed by a moving bicycle is:
Answer: C. Kinetic energy
Kinetic energy is the energy possessed by an object due to its motion. The faster an object moves, the greater its kinetic energy.
Quick Revision
• Kinetic energy is the energy of motion.
• Every moving object possesses kinetic energy.
• Greater speed results in greater kinetic energy.
Real-Life Example
A bicycle moving along a road has kinetic energy, which enables it to continue moving until brakes or friction slow it down.
13. Which of the following is a non-renewable source of energy?
Answer: C. Petroleum
Petroleum is a fossil fuel formed from the remains of ancient plants and animals over millions of years. Since it cannot be replenished within a short period, it is classified as a non-renewable source of energy.
Quick Revision
• Petroleum is a fossil fuel.
• It is a non-renewable energy source.
• Fossil fuels take millions of years to form.
Real-Life Example
Petrol and diesel used in vehicles are refined from petroleum, making it one of the most widely used non-renewable energy resources.
14. Which energy conversion takes place in an electric iron?
Answer: A. Electrical energy → Heat energy
An electric iron converts electrical energy into heat energy using a heating element. The generated heat is used to remove wrinkles from clothes during ironing.
Quick Revision
• Electric iron converts electrical energy into heat energy.
• A heating element produces the required heat.
• Heat energy is used for ironing clothes.
Real-Life Example
When you switch on an electric iron, the heating element becomes hot and helps smooth clothes by transferring heat to the fabric.
15. The main purpose of using renewable energy sources is to:
Answer: B. Reduce dependence on fossil fuels
Renewable energy sources such as solar, wind, and biogas are naturally replenished. Their use helps conserve fossil fuels, reduces environmental pollution, and supports sustainable energy development.
Quick Revision
• Renewable energy sources can be naturally replenished.
• They reduce dependence on fossil fuels.
• They help protect the environment by lowering pollution.
Real-Life Example
Installing solar panels on rooftops allows households to generate clean electricity, reducing the consumption of coal-based electricity and saving energy costs.
16. Water stored behind a dam possesses mainly:
Answer: B. Potential energy
Water stored behind a dam possesses gravitational potential energy because it is held at a height above the ground. When released, this stored energy is converted into kinetic energy, which rotates turbines to generate electricity.
Quick Revision
• Water stored at a height has gravitational potential energy.
• Potential energy changes into kinetic energy when water flows.
• Hydroelectric power plants use this energy transformation to generate electricity.
Real-Life Example
When the gates of a dam are opened, the flowing water spins turbines to produce electricity for homes and industries.
17. Which of the following is the SI unit of energy?
Answer: B. Joule
The joule (J) is the SI unit of energy and work. One joule is the energy transferred when a force of one newton moves an object through a distance of one metre in the direction of the force.
Quick Revision
• SI unit of energy = Joule (J).
• SI unit of power = Watt (W).
• Commercial unit of electrical energy = Kilowatt-hour (kWh).
Real-Life Example
Lifting a small object using a force over a short distance requires energy, which is measured in joules.
18. Which of the following best demonstrates the law of conservation of energy?
Answer: A. Swinging pendulum
A swinging pendulum demonstrates the law of conservation of energy because its potential energy continuously changes into kinetic energy and back again. The total mechanical energy remains nearly constant if friction and air resistance are neglected.
Quick Revision
• Potential energy converts into kinetic energy and vice versa.
• Total energy remains constant.
• Energy is transformed, not created or destroyed.
Real-Life Example
As a playground swing moves back and forth, its energy keeps changing between potential and kinetic energy while the total energy remains nearly constant.
19. Which of the following energy sources depends directly on sunlight?
Answer: A. Solar energy
Solar energy is obtained directly from the Sun’s radiation using devices such as solar panels and solar cookers. It is a clean, renewable source of energy that does not produce air pollution during electricity generation.
Quick Revision
• Solar energy comes directly from sunlight.
• It is a renewable and non-polluting source of energy.
• Solar panels convert sunlight into electrical energy.
Real-Life Example
Many homes and schools use rooftop solar panels to generate electricity from sunlight and reduce electricity bills.
20. Energy is defined as the:
Answer: C. Capacity to do work
Energy is the capacity to do work. It exists in different forms such as kinetic, potential, heat, light, electrical, chemical, and sound energy, and can be transformed from one form to another.
Quick Revision
• Energy is the capacity to do work.
• Energy exists in many different forms.
• Energy can neither be created nor destroyed.
Real-Life Example
A charged battery stores chemical energy, which is converted into electrical energy to operate devices such as a torch or a mobile phone.
Further Reading:
After completing this grand revision test, revisit the official NCERT chapter link given below to reinforce important Energy concepts. Reading the chapter again will help you connect the theory behind work, power, different forms of energy, and the law of conservation of energy, making your TNPSC Physics preparation more effective.
Official NCERT Textbook:
https://ncert.nic.in/textbook.php?iesc1=7-13
