Electricity is one of the most important topics in TNPSC General Science. Understanding concepts such as electric current, voltage, resistance, and Ohm’s Law helps in solving many Physics questions. Test your knowledge with this TNPSC Physics Electricity Quiz 1 and strengthen your exam preparation.
TNPSC Physics Electricity Quiz 1 – Detailed Explanations:
Electricity is the movement of electric charge through a conductor. It powers our homes, industries, and electronic devices, making it an essential part of everyday life. This topic covers fundamental concepts such as electric current, voltage, resistance, electric power, and simple electrical circuits, which are frequently tested in TNPSC examinations.
1. The SI unit of electric current is:
The ampere (A) is the SI unit used to measure electric current, which is the rate of flow of electric charge through a conductor. When electric charges, mainly electrons, move through a wire, an electric current is produced. One ampere is defined as the flow of one coulomb of charge per second. The unit is named after the French physicist André-Marie Ampère, who made significant contributions to the study of electromagnetism. Measuring current accurately is essential in designing and maintaining electrical circuits used in homes, industries, and electronic devices.
Key Points
- Electric current is measured in ampere (A).
- One ampere equals one coulomb per second.
- Current is the flow of electric charge.
- SI unit of current is named after André-Marie Ampère.
- Electric current is measured using an ammeter.
✅ Correct Answer: C. Ampere
2. The device used to measure electric current is:
An ammeter is an electrical instrument used to measure the amount of electric current flowing through a circuit. To obtain an accurate reading, it is always connected in series with the electrical circuit so that the entire current passes through it. An ideal ammeter has very low resistance, ensuring that it does not significantly affect the current being measured. Ammeters are commonly used in laboratories, industries, and electrical maintenance work to monitor the performance of electrical circuits and equipment.
Key Points
- An ammeter measures electric current.
- It is connected in series with the circuit.
- An ideal ammeter has very low resistance.
- Current is measured in amperes (A).
- Ammeters are widely used in electrical testing.
✅ Correct Answer: A. Ammeter
3. The SI unit of electrical resistance is:
Resistance is the property of a conductor that opposes the flow of electric current. The SI unit of resistance is the ohm (Ω), named after the German physicist Georg Simon Ohm. A conductor with high resistance allows less current to flow, while one with low resistance allows current to pass more easily. Resistance depends on factors such as the length, thickness, material, and temperature of the conductor. Understanding resistance is essential for designing safe and efficient electrical circuits.
Key Points
- Resistance is measured in ohms (Ω).
- It opposes the flow of electric current.
- The unit is named after Georg Simon Ohm.
- Resistance depends on the material, length, and thickness of a conductor.
- Copper has low resistance, making it suitable for wiring.
✅ Correct Answer: B. Ohm
4. The device used to measure voltage is:
A voltmeter is an instrument used to measure the potential difference (voltage) between two points in an electrical circuit. It is always connected in parallel across the component whose voltage is to be measured. An ideal voltmeter has very high resistance, allowing it to measure voltage without drawing significant current from the circuit. Voltmeters are commonly used in laboratories, power systems, and electrical troubleshooting to ensure that electrical devices operate within their specified voltage range.
Key Points
- A voltmeter measures potential difference (voltage).
- It is connected in parallel with the circuit component.
- An ideal voltmeter has very high resistance.
- Voltage is measured in volts (V).
- Voltmeters help monitor electrical circuits safely.
✅ Correct Answer: D. Voltmeter
5. Ohm’s Law states that:
Ohm’s Law explains the relationship between voltage, current, and resistance in an electrical circuit. It states that the current flowing through a conductor is directly proportional to the potential difference across it, provided the temperature and other physical conditions remain constant. This relationship is expressed by the equation V = IR, where V is voltage, I is current, and R is resistance. Ohm’s Law is one of the most fundamental principles of Electricity and is widely used to calculate unknown electrical quantities in circuits.
Key Points
- Ohm’s Law is represented by V = IR.
- Current is directly proportional to voltage.
- Resistance opposes the flow of current.
- The law is valid when temperature remains constant.
- It is widely used in electrical circuit calculations.
✅ Correct Answer: A. V = I × R
6. The SI unit of electric power is:
Electric power is the rate at which electrical energy is converted into other forms of energy or consumed in an electrical circuit. Its SI unit is the watt (W), named after the Scottish engineer James Watt. One watt is equal to one joule of energy used per second. Electrical appliances such as fans, bulbs, heaters, and refrigerators are rated in watts to indicate how much power they consume during operation. Understanding electric power helps in selecting energy-efficient appliances and calculating electricity consumption.
Key Points
- Electric power is measured in watt (W).
- One watt equals one joule per second.
- The unit is named after James Watt.
- Appliance ratings are usually given in watts.
- Electric power indicates the rate of energy consumption.
✅ Correct Answer: B. Watt
7. Which material is a good conductor of electricity?
A good conductor allows electric current to flow easily because it has a large number of free electrons. Copper is one of the best conductors of electricity and is widely used in electrical wiring, motors, transformers, and household appliances. It has low electrical resistance, high conductivity, and excellent durability. These properties make copper an ideal material for transmitting electrical energy efficiently with minimal power loss. Although silver has slightly higher conductivity, copper is preferred because it is more economical and readily available.
Key Points
- Copper is an excellent conductor of electricity.
- It has low electrical resistance.
- Copper is widely used in electrical wiring.
- Conductors contain free electrons.
- Copper is durable and cost-effective.
✅ Correct Answer: C. Copper
8. Which material is an insulator?
An insulator is a material that does not allow electric current to pass through it easily because it has very few free electrons. Plastic is one of the most commonly used insulating materials in electrical systems. It is used to cover electric wires, plugs, switches, and cables to prevent electric shocks and short circuits. Other common insulators include rubber, glass, and dry wood. Using proper insulating materials is essential for electrical safety in homes, industries, and workplaces.
Key Points
- Plastic is an electrical insulator.
- Insulators resist the flow of electric current.
- Plastic is used to cover electrical wires.
- Rubber and glass are also good insulators.
- Insulators help prevent electric shocks.
✅ Correct Answer: C. Plastic
9. The flow of electric charge is called:
Electric current is the continuous flow of electric charges through a conductor. In metallic conductors, this movement is mainly due to electrons. Current flows only when there is a potential difference across a conductor and a closed circuit is available. It is measured in amperes (A) using an ammeter. Electric current is responsible for operating electrical appliances such as lights, fans, televisions, and computers. Understanding the flow of current is fundamental to studying electrical circuits and their practical applications.
Key Points
- Electric current is the flow of electric charge.
- In metals, current is carried by electrons.
- Current flows only in a closed circuit.
- The SI unit of current is the ampere (A).
- Electric current powers electrical devices.
✅ Correct Answer: D. Electric Current
10. Electrical energy is commonly measured in:
Electrical energy consumed in homes and industries is commonly measured in kilowatt-hour (kWh), which is known as the commercial unit of electricity. One kilowatt-hour represents the energy consumed by a 1000-watt appliance operating for one hour. Electricity boards use this unit to calculate monthly electricity bills because it is more practical than using joules for large amounts of energy. Understanding the relationship between power, time, and energy helps consumers estimate electricity usage and promote energy conservation.
Key Points
- Kilowatt-hour (kWh) is the commercial unit of electrical energy.
- 1 kWh = 1000 watt-hours.
- Electricity bills are calculated in kWh (units).
- One unit of electricity equals 1 kWh.
- Electrical energy depends on power and time.
✅ Correct Answer: C. Kilowatt-hour (kWh)
11. The instrument used to detect small electric currents is:
A galvanometer is a highly sensitive instrument used to detect and measure very small electric currents in a circuit. Unlike an ammeter, which measures larger currents, a galvanometer responds to tiny current flows by causing its pointer to deflect. It is commonly used in laboratories and scientific experiments to study electrical circuits. A galvanometer can also be modified into an ammeter or voltmeter by adding suitable resistors. Its sensitivity makes it an important instrument for detecting the presence and direction of electric current.
Key Points
- A galvanometer detects small electric currents.
- It is more sensitive than an ammeter.
- It is mainly used in laboratories and experiments.
- The pointer deflects when current flows.
- A galvanometer can be converted into an ammeter or voltmeter.
✅ Correct Answer: A. Galvanometer
12. Which scientist discovered electromagnetic induction?
Michael Faraday, an English scientist, discovered electromagnetic induction in 1831. He found that moving a magnet near a coil of wire or changing the magnetic field around a conductor can produce an electric current. This discovery became the foundation for the working of electric generators, transformers, and many modern electrical devices. Faraday’s experiments established the relationship between electricity and magnetism, leading to significant advancements in electrical engineering and power generation. His contribution remains one of the most important milestones in the history of Physics.
Key Points
- Michael Faraday discovered electromagnetic induction.
- The discovery was made in 1831.
- A changing magnetic field can produce electric current.
- It is the working principle of generators and transformers.
- Faraday made major contributions to electromagnetism.
✅ Correct Answer: B. Michael Faraday
13. The device used to convert electrical energy into mechanical energy is:
An electric motor is a device that converts electrical energy into mechanical energy. It works on the principle that a current-carrying conductor placed in a magnetic field experiences a force, causing it to rotate. Electric motors are widely used in household appliances such as fans, mixers, washing machines, water pumps, and electric vehicles. They play an important role in industries by operating machines efficiently. The efficiency and reliability of electric motors make them one of the most widely used electrical devices in everyday life.
Key Points
- An electric motor converts electrical energy into mechanical energy.
- It works using electric current and magnetic fields.
- Motors are used in fans, pumps, and washing machines.
- They are widely used in industries and households.
- Electric motors make mechanical work easier and more efficient.
✅ Correct Answer: D. Motor
14. A fuse is used in electric circuits to:
A fuse is a safety device used to protect electrical circuits and appliances from damage caused by excessive current. It contains a thin wire made of a material with a low melting point. When the current exceeds the safe limit due to overloading or a 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. Choosing the correct fuse rating is essential for ensuring the safe operation of electrical systems.
Key Points
- A fuse protects electrical appliances from excess current.
- It contains a low melting point wire.
- The fuse melts during overloading or short circuits.
- It automatically breaks the circuit.
- Fuses improve electrical safety.
✅ Correct Answer: C. Protect appliances
15. The SI unit of electric charge is:
Electric charge is the fundamental property of matter responsible for electrical phenomena such as attraction and repulsion. The SI unit of electric charge is the coulomb (C), named after the French physicist Charles-Augustin de Coulomb. One coulomb is defined as the amount of charge carried by a current of one ampere in one second. Electric charge exists in two forms—positive and negative—and is carried by protons and electrons. Measuring electric charge is essential for understanding electric current, electric fields, and electrical circuits.
Key Points
- Electric charge is measured in coulombs (C).
- 1 coulomb = 1 ampere × 1 second.
- Charge exists as positive and negative.
- Electrons carry negative charge.
- The unit is named after Charles-Augustin de Coulomb.
✅ Correct Answer: B. Coulomb
16. The energy stored in a battery is:
A battery stores chemical energy, which is converted into electrical energy when it is connected to a circuit. This conversion takes place through chemical reactions inside the battery, causing electrons to flow through the external circuit and produce electric current. Batteries are widely used in devices such as mobile phones, clocks, flashlights, remote controls, and electric vehicles. Once the chemical energy is exhausted, the battery must be recharged or replaced, depending on its type. Batteries provide a convenient and portable source of electrical energy for many everyday applications.
Key Points
- Batteries store chemical energy.
- Chemical energy is converted into electrical energy.
- Chemical reactions inside the battery produce electric current.
- Batteries are used in portable electronic devices.
- Rechargeable batteries can be used multiple times.
✅ Correct Answer: B. Chemical Energy
17. The heating effect of electric current is used in:
When electric current passes through a conductor with resistance, a part of the electrical energy is converted into heat energy. This phenomenon is known as the heating effect of electric current or Joule heating. Electrical appliances such as heaters, electric irons, kettles, geysers, and toasters operate using this principle. The amount of heat produced depends on the resistance of the conductor, the current flowing through it, and the duration for which the current flows. This effect is useful in many domestic and industrial applications.
Key Points
- The heating effect converts electrical energy into heat.
- Electric heaters work on this principle.
- Electric irons, kettles, and geysers also use this effect.
- Heat depends on current, resistance, and time.
- This principle is known as Joule heating.
✅ Correct Answer: A. Electric Heater
18. Which of the following is used to step up or step down voltage?
A transformer is an electrical device used to increase (step up) or decrease (step down) the voltage of alternating current (AC). It works on the principle of electromagnetic induction, where a changing magnetic field induces voltage in another coil. Step-up transformers are used to increase voltage for efficient power transmission over long distances, while step-down transformers reduce voltage before electricity reaches homes and industries. Transformers are essential components of modern power distribution systems because they help minimize energy loss during transmission.
Key Points
- A transformer changes the voltage of AC.
- It can step up or step down voltage.
- It works on electromagnetic induction.
- Transformers improve the efficiency of power transmission.
- They operate only with alternating current (AC).
✅ Correct Answer: D. Transformer
19. Static electricity is produced by:
Static electricity is produced when electrons are transferred from one material to another due to friction. Rubbing materials such as a plastic comb against dry hair or a balloon against wool causes one object to gain electrons while the other loses them. This creates an imbalance of electric charges on the surfaces of the materials. Since these charges remain at rest until discharged, they are called static electricity. Everyday examples include clothes sticking together after drying and small electric shocks experienced after walking on a carpet.
Key Points
- Static electricity is produced mainly by friction.
- It is caused by the transfer of electrons.
- Charges remain stationary until discharged.
- Rubbing a balloon on hair is a common example.
- Static electricity can produce small electric sparks.
✅ Correct Answer: B. Friction
20. Lightning is an example of:
Lightning is a natural phenomenon caused by the sudden discharge of static electric charges that accumulate within clouds or between clouds and the Earth. During thunderstorms, collisions between ice particles and water droplets create large amounts of electrical charge. When the potential difference becomes very high, the accumulated charges are released as a powerful electrical discharge, producing a bright flash of light and the sound of thunder. Lightning demonstrates the effects of static electricity on a large scale and plays an important role in atmospheric electrical processes.
Key Points
- Lightning is caused by static electric charges.
- It occurs between clouds or between clouds and the Earth.
- It is accompanied by thunder.
- Lightning is a natural electrical discharge.
- It is an example of static electricity.
✅ Correct Answer: A. Static Electricity
Exam Tips
- Remember the SI units: Current – Ampere (A), Resistance – Ohm (Ω), Power – Watt (W), Charge – Coulomb (C).
- Ammeter measures electric current and is connected in series.
- Voltmeter measures potential difference and is connected in parallel.
- Revise Ohm’s Law (V = IR) and understand the relationship between voltage, current, and resistance.
- Learn the difference between conductors (Copper) and insulators (Plastic, Rubber).
- Remember that 1 unit of electricity = 1 kilowatt-hour (kWh).
- Understand the working principles of electric motor, transformer, battery, and fuse.
- Know the uses of the heating effect of electric current in everyday appliances.
- Revise important scientists such as Andre-Marie Ampere, Georg Simon Ohm, Michael Faraday, and James Watt along with their contributions.
- Practice previous TNPSC General Science questions to improve speed and accuracy.
Further Reading
To strengthen your understanding of Electricity, refer to the official NCERT Class 10 Science textbook and study Chapter 12 – Electricity. The chapter explains electric current, potential difference, resistance, Ohm’s Law, electrical power, and the heating effect of electric current through simple explanations and practical examples. Regular study of this chapter will help build a strong foundation for TNPSC General Science preparation.
Official NCERT Textbook: Chapter 12 – Electricity
