Class 7 Science Chapter 10 Important Question Answers - Electric Current and Its effects

Very Short Answer Type Questions

Q1: What are electric components?
Ans: Electric components are devices that manipulate or control the flow of electricity in a circuit, such as resistors, capacitors, inductors, diodes, and transistors.

Q2: What is a circuit diagram?
Ans: A circuit diagram is a simplified pictorial representation of an electrical circuit that uses standardized symbols for electric components.

Q3: Define an electrical circuit.
Ans: An electrical circuit is a closed path formed by interconnecting electrical components through which electric current flows.

Q4: What is the purpose of a cell holder?
Ans: A cell holder is a compartment that holds two or more cells together to form a battery.

Q5: Differentiate between an open circuit and a closed circuit.
Ans: An open circuit is incomplete and does not allow current to flow, while a closed circuit is complete and allows current to flow.

Q6: What is the ISI mark on electrical appliances?
Ans: The ISI mark stands for Indian Standards Institute and signifies that an appliance is safe, energy-efficient, and of good quality.

Q7: Explain the heating effect of electric current.
Ans: The heating effect of electric current refers to the generation of heat when electric current flows through a conductor, as observed in devices like electric bulbs and heaters.

Q8: Why are Compact Fluorescent Lamps (CFLs) more energy-efficient than ordinary bulbs?
Ans: CFLs do not rely on the heating effect of electric current to produce light, resulting in less energy wastage compared to ordinary bulbs.

Q9: What is an electromagnet?
Ans: An electromagnet is a magnet formed when electric current flows through a wire wound around an iron core, creating a magnetic field.

Q10: How does an electric bell work?
Ans: An electric bell works by using an electromagnet to attract a hammer, which strikes the bell to produce a sound. The circuit repeatedly breaks and completes to create the ringing effect.

Short Answer Type Questions

Q11: Explain the purpose of electric components in an electrical circuit.
Ans: Electric components are essential in electrical circuits as they serve various functions, such as regulating current, storing energy, and converting energy forms. They manipulate the flow of electricity to enable devices to function correctly.

Q12: Describe the difference between an open circuit and a closed circuit.
Ans: An open circuit is incomplete, allowing no flow of electric current. It is often caused by a disconnected wire or an off-switch. In contrast, a closed circuit is complete, enabling the flow of electric current through interconnected components.

Q13: What is the significance of the ISI mark on electrical appliances?
Ans: The ISI mark assures consumers that an electrical appliance meets safety and quality standards. It indicates that the appliance is less likely to waste electrical energy and is designed to function safely.

Q14: How does an electromagnet work, and what are its applications?
Ans: An electromagnet is formed when current flows through a coil of wire wound around an iron core, creating a magnetic field. Electromagnets are used in various applications, such as electric bells, cranes, electromagnetic trains (Maglev), and lifting devices.

Q15: Explain the heating effect of electric current and provide examples.
Ans: The heating effect of electric current refers to the generation of heat when current flows through a conductor. Examples include electric bulbs, electric room heaters, toasters, and electric irons, all of which produce heat through this effect.

Q16: What is the purpose of an electric fuse, and how does it work?
Ans: An electric fuse is a safety device that prevents damage to electrical circuits due to excessive current. It contains a wire that melts when current exceeds a limit, breaking the circuit and preventing fires.

Q17: Why are Miniature Circuit Breakers (MCBs) preferred over traditional fuses?
Ans: MCBs are preferred because they are automatic switches that turn off during overload or short circuit conditions and can be easily reset after resolving the issue. Traditional fuses need replacement when blown.

Q18: How does an electric bell function, and what components are involved?
Ans: An electric bell uses an electromagnet to attract a hammer, which strikes the bell to produce a sound. Components include an iron core, a coil of wire, a hammer, a bell, and a switch to complete the circuit.

Q19: Explain the concept of the magnetic effect of electric current.
Ans: The magnetic effect of electric current refers to the creation of a magnetic field around a current-carrying wire or coil. It was discovered by Hans Christian Oersted and is the principle behind electromagnets.

Q20: Describe the construction and working of an electromagnet.
Ans: An electromagnet is created by winding a coil of wire around an iron core. When current flows through the coil, the iron core becomes magnetized. This principle is used in applications like cranes and electromagnetic trains.