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Chapter Analysis
Beginner13 pages • EnglishQuick Summary
The chapter 'Electric Current and its Effects' covers basic concepts of electric current, its heating and magnetic effects, and the construction and function of electromagnets. It explains practical applications such as electric fuses and miniature circuit breakers for safety. The chapter also includes experiments to understand the behavior of electric circuits and demonstrates how electric currents can create magnetic effects.
Key Topics
- •Symbols of Electric Components
- •Heating Effect of Current
- •Magnetic Effect of Current
- •Electromagnets
- •Electric Bell
- •Safety Devices in Circuits
- •Circuit Diagrams
- •Energy Efficiency in Lighting
Learning Objectives
- ✓Understand the symbols used for representing electric components.
- ✓Comprehend the heating effect of electric current and its applications.
- ✓Explore the magnetic effects of electric current and how they are utilized.
- ✓Identify and illustrate the workings of an electromagnet.
- ✓Explain the operation of an electric bell.
- ✓Recognize the importance of safety devices such as fuses in electrical circuits.
Questions in Chapter
Draw in your notebook the symbols to represent the following components of electrical circuits: connecting wires, switch in the 'OFF' position, bulb, cell, switch in the 'ON' position, and battery.
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Draw the circuit diagram to represent the circuit shown in Fig.10.21.
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Fig.10.22 shows four cells fixed on a board. Draw lines to indicate how you will connect their terminals with wires to make a battery of four cells.
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The bulb in the circuit shown in Fig.10.23 does not glow. Can you identify the problem? Make necessary changes in the circuit to make the bulb glow.
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Name any two effects of electric current.
Answer: The heating effect and the magnetic effect.
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When the current is switched on through a wire, a compass needle kept nearby gets deflected from its north-south position. Explain.
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Will the compass needle show deflection when the switch in the circuit shown by Fig.10.24 is closed?
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Fill in the blanks: (a) Longer line in the symbol for a cell represents its ____ terminal. (b) The combination of two or more cells is called a _____. (c) When current is switched 'on' in a room heater, it _____. (d) The safety device based on the heating effect of electric current is called a _____.
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Mark 'T' if the statement is true and 'F' if it is false: (a) To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell. (T/F) (b) When the electric current through the fuse exceeds a certain limit, the fuse wire melts and breaks. (T/F) (c) An electromagnet does not attract a piece of iron. (T/F) (d) An electric bell has an electromagnet. (T/F)
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Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.
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An electrician is carrying out some repairs in your house. He wants to replace a fuse by a piece of wire. Would you agree? Give reasons for your response.
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Zubeda made an electric circuit using a cell holder shown in Fig. 10.4, a switch and a bulb. When she put the switch in the 'ON' position, the bulb did not glow. Help Zubeda in identifying the possible defects in the circuit.
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In the circuit shown in Fig. 10.25 (i) Would any of the bulb glow when the switch is in the 'OFF' position? (ii) What will be the order in which the bulbs A, B and C will glow when the switch is moved to the 'ON' position?
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Additional Practice Questions
What causes an electric wire to get hot when an electric current flows through it?
mediumAnswer: The heating effect of electric current causes the wire to get hot. This effect is due to the resistance of the wire, which converts electrical energy into heat energy.
Why should we not replace a blow fuse with just any wire? Explain the importance of using proper fuses.
mediumAnswer: A proper fuse is designed to melt and break the circuit if the current exceeds a safe limit. Using just any wire can prevent this safety function, potentially leading to overheated wires and fires.
Explain how a circuit diagram is different from a real circuit, and why engineers prefer using diagrams.
easyAnswer: A circuit diagram uses standardized symbols to represent components, making it easier to understand and communicate electrical designs without needing to see physical components.
Discuss the role of an electromagnet in an electric bell.
mediumAnswer: An electromagnet attracts an iron strip in an electric bell, which then completes the circuit and causes the hammer to strike the bell. When the magnet pulls the strip, it breaks the circuit, stopping the current and allowing the strip to move back.
What is the advantage of using LEDs over incandescent bulbs for lighting?
easyAnswer: LEDs are more energy-efficient, consuming less electricity to produce the same amount of light as incandescent bulbs, leading to reduced electricity costs.
NCERT Exemplar
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