Electric current and its effects class 7 extra questions
Answers
Ans:Electric Current is the flow of electrons. But an electric Circuit is the closed path in which electric current flows.
Q2: Explain the formation and uses of battery.
Ans:A combination of two or more cells connected together is called a battery. It supplies electric current. It is formed by connecting the positive terminal of one cell to the negative terminal of another. To identify the positive and negative terminals, they are denoted as + and –, respectively. These batteries are used in many devices, such as torch lights, mobile phones, calculators and even automobiles.
Q3: Explain the function of cell in a circuit.
Ans:A cell supplies electric current.The positive terminal (+)of a cell is represented by a vertical long line, while thenegative terminal (-) is shown as a parallel, shorter line.
Q4: 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.
Ans: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.
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Q1: Differentiate between electric current and electric circuit.
Ans:Electric Current is the flow of electrons. But an electric Circuit is the closed path in which electric current flows.
Q2: Explain the formation and uses of battery.
Ans:A combination of two or more cells connected together is called a battery. It supplies electric current. It is formed by connecting the positive terminal of one cell to the negative terminal of another. To identify the positive and negative terminals, they are denoted as + and –, respectively. These batteries are used in many devices, such as torch lights, mobile phones, calculators and even automobiles.
Q3: Explain the function of cell in a circuit.
Ans:A cell supplies electric current.The positive terminal (+)of a cell is represented by a vertical long line, while thenegative terminal (-) is shown as a parallel, shorter line.
Q4: 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.
Ans: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.