Prepare for your upcoming TNPSC exams you need TNPSC Physics Electricity Test 2, which carefully selected multiple-choice questions from the Electricity topic. This TNPSC Physics Quiz helps you strengthen key concepts. This Test 2 covers important Electricity topics from the TNPSC General Science syllabus, including series and parallel circuits, household wiring, earthing, electrical safety, electromagnets, heating effect of electric current, AC supply, MCB, electrical resistance, and renewable sources of electricity..
TNPSC Physics Electricity Test 2 – Detailed Explanations For Each Questions
After completing TNPSC Physics Electricity Test 2, review each answer with clear explanations to reinforce your understanding. These TNPSC Electricity Questions explanations highlight important Electricity concepts, common exam patterns, and practical points to help you perform better in the TNPSC General Science section. Electricity Questions are from important topics of TNPSC General Science syllabus, including series and parallel circuits, household wiring, earthing, electrical safety, electromagnets, heating effect of electric current, AC supply, MCB, electrical resistance, and renewable sources of electricity.
1. Which of the following materials has the highest electrical resistivity?
Answer: Rubber
Explanation:
Electrical resistivity is the property of a material that opposes the flow of electric current. Materials with high resistivity do not allow electricity to pass through them easily and are known as insulators. Rubber has extremely high electrical resistivity, making it an excellent insulating material. It is widely used to cover electrical wires, cables, and safety gloves to protect people from electric shock. In contrast, metals such as copper, aluminium, and silver have very low resistivity and are good conductors of electricity. Among them, silver is the best conductor, while copper is the most commonly used for electrical wiring due to its excellent conductivity and lower cost. Therefore, rubber has the highest electrical resistivity among the given materials.
Quick Revision:
- Electrical resistivity measures opposition to electric current.
- Rubber is an excellent electrical insulator.
- Copper and aluminium are widely used as conductors.
- Silver has the highest electrical conductivity among metals.
Real-Life Example:
The rubber coating on electrical wires prevents electric shocks by stopping electric current from passing through to the user.
2. In a series circuit, if one bulb fuses, what happens to the other bulbs?
Answer: They stop glowing.
Explanation:
A series circuit consists of electrical components connected one after another in a single continuous path. Since there is only one path for electric current to flow, the same current passes through every component in the circuit. If one bulb fuses, the filament inside it breaks, creating an open circuit. This interrupts the flow of electric current throughout the entire circuit. As a result, none of the remaining bulbs receive electricity, and they all stop glowing. This is one of the main disadvantages of a series circuit. Because of this limitation, household electrical wiring uses parallel circuits instead of series circuits, ensuring that one faulty appliance does not affect the operation of others.
Quick Revision:
- A series circuit has only one path for electric current.
- The same current flows through all components in a series circuit.
- If one component fails, the entire circuit becomes open.
- Household appliances are connected in parallel, not in series.
Real-Life Example:
Older decorative string lights connected in series often go completely dark when a single bulb burns out because the circuit is broken.
3. Household electrical appliances are generally connected in:
Answer: Parallel
Explanation:
Household electrical appliances are connected in parallel because this arrangement allows every appliance to receive the full supply voltage independently. In a parallel circuit, each appliance has its own path for electric current. This means that if one appliance is switched off or becomes faulty, the others continue to function normally. Another advantage is that each appliance can be controlled using its own switch without affecting the operation of other devices. Parallel wiring also ensures that appliances operate at their rated voltage, making it the safest and most efficient method for domestic electrical installations.
Quick Revision:
- Household wiring uses parallel connections.
- Each appliance receives the full supply voltage.
- Appliances work independently of one another.
- Parallel circuits improve convenience and safety.
Real-Life Example:
When you switch off the ceiling fan, the lights and television continue to work because they are connected in parallel.
4. The purpose of earthing is to:
Answer: Prevent electric shock
Explanation:
Earthing is an important safety feature in electrical systems that protects people from electric shock. It involves connecting the metal body of an electrical appliance to the ground through an earth wire. If insulation fails or a live wire accidentally touches the metal body, the leakage current flows safely into the earth instead of passing through a person. This reduces the risk of electric shock and helps safety devices such as fuses and Miniature Circuit Breakers (MCBs) disconnect the faulty circuit quickly. Proper earthing is compulsory for many household appliances with metal bodies.
Quick Revision:
- Earthing protects users from electric shock.
- Leakage current is safely transferred to the ground.
- Earthing is essential for metal-bodied appliances.
- It works together with fuses and MCBs for electrical safety.
Real-Life Example:
A washing machine is connected to an earth wire so that any leakage current is safely discharged into the ground, protecting the user.
5. Which component acts as the source of electrical energy in a simple electric circuit?
Answer: Cell
Explanation:
A cell is the basic source of electrical energy in a simple electric circuit. It converts chemical energy into electrical energy through chemical reactions occurring inside it. This process creates a potential difference between its positive and negative terminals, causing electric current to flow when the circuit is complete. Without a cell or battery, electrical components such as bulbs, buzzers, or LEDs cannot operate. In larger electrical systems, generators or power supplies perform the same function, but in simple circuits, a cell is the primary energy source.
Quick Revision:
- A cell converts chemical energy into electrical energy.
- It provides the potential difference required for current flow.
- A complete circuit needs an energy source.
- Batteries consist of one or more connected cells.
Real-Life Example:
A flashlight works because the dry cells inside it supply electrical energy to the LED or bulb when the switch is turned on.
6. A switch in an electric circuit is used to:
Answer: Open or close the circuit
Explanation:
A switch is a device used to control the flow of electric current in a circuit. When the switch is closed (ON), it completes the circuit, allowing current to flow and electrical devices to operate. When the switch is opened (OFF), it breaks the circuit, stopping the flow of current. Switches are essential components in homes, schools, industries, and electronic devices because they provide a safe and convenient way to control electrical equipment without disconnecting the power source.
Quick Revision:
- A switch controls the flow of electric current.
- Closing the switch completes the circuit.
- Opening the switch breaks the circuit.
- Switches improve safety and convenience.
Real-Life Example:
Pressing the wall switch turns a room light on or off by completing or breaking the electrical circuit.
7. Which wire is normally connected to the Earth pin in a three-pin plug?
Answer: Earth wire
Explanation:
A three-pin plug contains three wires: the live wire, neutral wire, and earth wire. The earth wire is connected to the longest and thickest pin, known as the earth pin. Its main purpose is to protect users from electric shock by providing a safe path for leakage current to flow into the ground. Under normal operating conditions, no current flows through the earth wire. However, during an electrical fault, it safely carries the leakage current away from the appliance, reducing the risk of injury and helping protective devices disconnect the circuit.
Quick Revision:
- A three-pin plug has live, neutral, and earth wires.
- The earth wire is connected to the longest pin.
- It provides protection against electric shock.
- Leakage current flows through the earth wire during faults.
Real-Life Example:
The metal body of a refrigerator is connected to the earth wire so that users remain safe even if an internal electrical fault occurs.
8. An electromagnet becomes magnetic when:
Answer: Electric current passes through it.
Explanation:
An electromagnet is created by winding insulated copper wire around a soft iron core. When electric current flows through the coil, it produces a magnetic field that magnetizes the soft iron core, causing it to behave like a magnet. Unlike a permanent magnet, an electromagnet remains magnetic only while current flows through it. When the current is switched off, the magnetic property disappears. The strength of an electromagnet can be increased by increasing the number of turns in the coil or the amount of electric current passing through it. Electromagnets are widely used in electrical devices because their magnetism can be controlled.
Quick Revision:
- An electromagnet works only when current flows.
- Soft iron is commonly used as the core.
- Magnetism disappears when the current is switched off.
- More coil turns increase magnetic strength.
Real-Life Example:
Electric cranes in scrapyards use powerful electromagnets to lift and release heavy iron objects.
9. Which metal is commonly used for making the filament of an electric bulb?
Answer: Tungsten
Explanation:
Tungsten is used as the filament material in incandescent electric bulbs because it has an extremely high melting point of about 3422°C, one of the highest among all metals. This allows the filament to become white-hot and emit light without melting. Tungsten also has good tensile strength and can be drawn into very thin wires, making it suitable for bulb filaments. Although LED bulbs are now more common due to their energy efficiency, traditional incandescent bulbs rely on tungsten filaments for producing light.
Quick Revision:
- Tungsten has a very high melting point.
- It glows brightly when heated by electric current.
- It is used in incandescent bulb filaments.
- LED bulbs are more energy-efficient than filament bulbs.
Real-Life Example:
Older household bulbs produced light by heating a thin tungsten filament until it glowed.
10. The heating effect of electric current is mainly due to:
Answer: Electrical resistance
Explanation:
When electric current flows through a conductor, the conductor resists the movement of electrons. This resistance converts part of the electrical energy into heat energy, a phenomenon known as the heating effect of electric current or Joule heating. Materials with higher resistance produce more heat when current passes through them. This principle is used in appliances such as electric irons, heaters, kettles, geysers, and toasters. While heat generation is useful in these appliances, excessive heating in electrical wires is undesirable because it wastes energy and may damage the circuit.
Quick Revision:
- Electrical resistance causes the heating effect.
- Electrical energy is converted into heat energy.
- Heating effect is useful in electric heating appliances.
- Excessive heating can damage electrical circuits.
Real-Life Example:
An electric iron becomes hot because its heating element has resistance that converts electrical energy into heat.
11. Which of the following is an electrical safety device?
Answer: Fuse
Explanation:
A fuse is an important electrical safety device that protects circuits and appliances from damage caused by excessive current. It consists of a thin wire made of a low-melting-point alloy. When the current exceeds the safe limit due to an overload or short circuit, the fuse wire melts and breaks the circuit, stopping the flow of electricity. This prevents overheating, fire hazards, and damage to electrical equipment. Although modern homes increasingly use MCBs, fuses are still widely used in many electrical installations.
Quick Revision:
- A fuse protects against overload and short circuits.
- Fuse wire has a low melting point.
- It breaks the circuit when current becomes excessive.
- Fuses improve electrical safety.
Real-Life Example:
If too many appliances are connected to one socket, the fuse may melt and disconnect the circuit to prevent damage.
12. Which of the following is a poor conductor of electricity?
Answer: Mica
Explanation:
Mica is a naturally occurring mineral that acts as an excellent electrical insulator because it does not allow electric current to pass through it easily. It also has high heat resistance, making it suitable for use in electrical and electronic equipment. Copper and aluminium are good conductors, while graphite, although a form of carbon, can also conduct electricity because of its free electrons. Due to its insulating properties, mica is commonly used in electrical appliances where both electrical insulation and heat resistance are required.
Quick Revision:
- Mica is an excellent electrical insulator.
- It can withstand high temperatures.
- Copper, aluminium, and graphite conduct electricity.
- Mica is widely used in electrical equipment.
Real-Life Example:
Mica sheets are used inside electric irons and heaters to safely insulate electrical components from metal parts.
13. Electric current can flow only when the circuit is:
Answer: Complete
Explanation:
Electric current can flow only through a complete or closed circuit. A complete circuit provides a continuous path from the source of electrical energy, through the electrical components, and back to the source. If the circuit is open, broken, or disconnected at any point, the flow of current stops immediately. This basic principle is essential for the operation of all electrical devices, from simple torchlights to complex household appliances. A switch works by opening or closing the circuit to control current flow.
Quick Revision:
- Current flows only in a closed circuit.
- A broken circuit stops current flow.
- A complete path is necessary for electricity.
- Switches control circuit continuity.
Real-Life Example:
A torch glows only when its switch closes the circuit, allowing current to flow through the bulb.
14. Which of the following works on the magnetic effect of electric current?
Answer: Electric bell
Explanation:
An electric bell operates on the magnetic effect of electric current. When current flows through the coil inside the bell, it produces a magnetic field that turns the soft iron core into an electromagnet. The electromagnet attracts an iron armature, causing the hammer to strike the bell and produce sound. As the contact breaks, the current stops, the electromagnet loses its magnetism, and the armature returns to its original position. This cycle repeats rapidly, producing a continuous ringing sound.
Quick Revision:
- An electric bell uses an electromagnet.
- Current produces a magnetic field.
- The armature strikes the bell repeatedly.
- The process continues while the switch remains closed.
Real-Life Example:
School bells and doorbells commonly use electromagnets to produce sound whenever the switch is pressed.
15. The resistance of a conductor depends on its:
Answer: Length, area and material
Explanation:
The resistance of a conductor depends on several factors, including its length, cross-sectional area, and the material from which it is made. A longer conductor offers greater resistance because electrons travel a greater distance. A conductor with a larger cross-sectional area has lower resistance since more electrons can flow simultaneously. Different materials have different resistivities, so conductors like copper have lower resistance than materials such as nichrome. Temperature also affects resistance, with the resistance of most metallic conductors increasing as temperature rises.
Quick Revision:
- Resistance increases with length.
- Resistance decreases with larger cross-sectional area.
- Different materials have different resistivities.
- Copper has lower resistance than nichrome.
Real-Life Example:
High-voltage transmission cables are made thick to reduce electrical resistance and minimize power loss.
16. Which appliance converts electrical energy mainly into light energy?
Answer: LED lamp
Explanation:
An LED (Light Emitting Diode) lamp is designed to convert electrical energy primarily into light energy with very little energy wasted as heat. Unlike traditional incandescent bulbs, which produce light by heating a tungsten filament, LED lamps generate light through the movement of electrons in a semiconductor material. This process is highly energy-efficient and results in lower electricity consumption and a longer lifespan. Because of these advantages, LED lamps have become the preferred choice for homes, offices, and street lighting. They are environmentally friendly and help reduce electricity bills while providing bright illumination.
Quick Revision:
- LED stands for Light Emitting Diode.
- LED lamps mainly convert electrical energy into light energy.
- LEDs consume less electricity than incandescent bulbs.
- LEDs have a longer lifespan and produce less heat.
Real-Life Example:
Most homes today use LED bulbs because they provide bright light while consuming much less electricity than traditional filament bulbs.
17. Which type of current is supplied to homes in India?
Answer: Alternating Current (AC)
Explanation:
Homes in India receive Alternating Current (AC) from the electricity distribution system. In AC, the direction of electric current changes periodically, making it suitable for transmitting electricity over long distances with minimal power loss. In India, the standard domestic electricity supply is 230 volts at a frequency of 50 hertz (50 Hz). Most household appliances such as fans, refrigerators, televisions, washing machines, and air conditioners are designed to operate on AC supply. In contrast, batteries provide Direct Current (DC), where current flows in only one direction.
Quick Revision:
- Indian homes receive Alternating Current (AC).
- Standard domestic supply is 230 V, 50 Hz.
- AC changes direction periodically.
- Batteries supply Direct Current (DC).
Real-Life Example:
When you plug a television or fan into a wall socket, it operates using the AC electricity supplied by the power grid.
18. Which instrument is used to protect an electric circuit from overload in modern houses?
Answer: MCB
Explanation:
An MCB (Miniature Circuit Breaker) is a modern electrical safety device that protects circuits from overloads and short circuits. When excessive current flows through the circuit, the MCB automatically trips and disconnects the electrical supply, preventing damage to appliances and reducing the risk of fire. Unlike a fuse, which must be replaced after melting, an MCB can simply be reset after the fault has been corrected. Due to its convenience, reliability, and improved safety, MCBs are widely used in modern homes and commercial buildings.
Quick Revision:
- MCB stands for Miniature Circuit Breaker.
- It protects against overload and short circuits.
- An MCB automatically trips during faults.
- It can be reset and reused after the problem is fixed.
Real-Life Example:
If too many high-power appliances are switched on at the same time, the MCB in the distribution board may trip to protect the electrical circuit.
19. Which of the following is a renewable source used to generate electricity?
Answer: Solar energy
Explanation:
Solar energy is a renewable source of energy because it is continuously supplied by the Sun and does not get exhausted through normal use. Solar panels convert sunlight directly into electrical energy using photovoltaic (PV) cells. Unlike fossil fuels such as coal, diesel, and petrol, solar energy does not produce harmful air pollutants or greenhouse gases during electricity generation. As a clean and sustainable energy source, solar power plays an important role in reducing dependence on non-renewable resources and protecting the environment.
Quick Revision:
- Solar energy is a renewable energy source.
- Solar panels convert sunlight into electricity.
- It is clean, sustainable, and environmentally friendly.
- Coal, diesel, and petrol are non-renewable energy sources.
Real-Life Example:
Many houses and schools install rooftop solar panels to generate electricity and reduce monthly electricity bills.
20. Which scientist invented the first practical electric incandescent lamp?
Answer: Thomas Alva Edison
Explanation:
Thomas Alva Edison is widely credited with developing the first practical electric incandescent lamp in 1879. Although several scientists had experimented with electric lighting before him, Edison improved the design by using a long-lasting carbon filament and creating a practical lighting system suitable for everyday use. His invention played a significant role in making electric lighting commercially successful and transforming homes, industries, and public spaces. Edison’s work also contributed greatly to the development of modern electrical power distribution systems.
Quick Revision:
- Thomas Alva Edison developed the first practical incandescent lamp.
- His successful lamp was introduced in 1879.
- Earlier scientists contributed to electric lighting research.
- Edison also helped develop practical electric power systems.
Real-Life Example:
The widespread use of electric bulbs in homes and streets began after Edison’s practical incandescent lamp made electric lighting commercially feasible.
Further Reading:
To build a stronger understanding of Electricity concepts beyond this quiz, explore the official NCERT Science chapter (Link Given below) covering electric current, circuits, resistance, and related concepts. Reading the textbook alongside practicing Electricity Questions with Answers will strengthen your fundamentals for TNPSC examinations.
Further Reading: Chapter 11 – Electricity
Well done on completing TNPSC Physics Electricity Test 2. Regular practice with TNPSC Electricity Questions and reviewing detailed explanations will improve both your accuracy and speed. Continue with the remaining TNPSC Physics Quiz series on CrackIndiaExams to strengthen every topic in the TNPSC General Science syllabus and boost your exam readiness.