The complete set of important questions for CBSE class 7th science prepared by our subject experts contains all the explanations and step by step solutions for the chapters and topics in science. Download free pdf for practise.
Important questions based on NCERT syllabus for Chapter 14 - Electric Current and Its Effects:
Question-1: An electrician is carrying out some repairs in a building. He wants to replace a fuse by a piece of wire. Would you agree with the electrician? Give reasons for your response.
Solution: There is a maximum limit on the current which can safely flow through a circuit. If by accident the current exceeds this safe limit, the wires may become overheated and may cause fire. In order to prevent this, in all buildings fuses are inserted in all electrical circuits. If a proper fuse is there in the circuit, it will blow off and break the circuit. A fuse is thus a safety device which prevents damages to electrical circuits and possible fires. So we will not agree with an
electrician, who is using a wire in place of fuse of proper rating as if by accident the current exceeds safe limit, the wires may become overheated and may cause fire.
Question-2: Explain the function of cell in a circuit?
Solution: A cell supplies electric current. The positive terminal of a cell is represented by a vertical long line, while the negative terminal is shown as parallel, shorter line.
Question-3: Can we use an electromagnet separating plastic bags from a garbage heap?
Solution: An electromagnet can be used to separate magnetic material from non-magnetic material. We cannot use electromagnet to separate plastic bags from a garbage heap as electromagnet only attracts magnetic material and plastic bags are non-magnetic material.