Q:
Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.
A:
Plastic bags are not magnetic substances and thus, electromagnets cannot be used for separating them from garbage heap.
Q:
Will the compass needle show deflection when the switch in the circuit shown by Fig.14.24 is closed?
A:
Yes, compass needle will show deflection when switch is closed in the given circuit.
Q:
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.
A:
Q:
Name any two effects of electric current.
A:
The two effects of electric current are as follows:
- Heating effect
- Magnetic effect
Q:
Fig.14.22 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.
A:
The correct connection of the terminals of four cells with wires to make a battery is as follows, in which positive side of one battery to the negative side of the other:
Q:
Draw the circuit diagram to represent the circuit shown in Fig.14.21.
A:
The electrical components and their relation with each other shown above can be represented by following circuit diagram:
Q:
In the circuit shown in Fig. 14.25
(i) Would any of the bulbs 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?
A:
(i) None of the bulbs will glow when switch is in the ‘OFF’ position because circuit remains incomplete and thus, no current will flow in it.
(ii) All the bulbs will glow at once when switch is moved to the ‘ON’ position.
Q:
Zubeda made an electric circuit using a cell holder shown in Fig. 14.4, 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.
A:
The possible defects which may be found in Zubeda’s circuit are as follows:
1. The terminals of cells are not connected to each other in the correct manner.
2. The connections of wires are loose.
3. The bulb used may have fuse.
Q:
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.
A:
No, electric fuse should not be replaced by a piece of wire. It is so because electric fuse protects the circuit against the flow of large amount of electric current which may cause short circuit and eventually fire in the house. Wire in the electric fuse is made up of some special material such that immediately melts down, if large amount of electric current passes through it and breaks down the circuit. Thus, electric fuse prevents short circuit and fires caused by electric current.
Q:
When the current is switched on through a wire, a compass needle kept nearby gets deflected from its north-south position. Explain.
A:
The deflection of compass needle in north-south position indicates that as soon as current is switched on through a wire, a magnetic field develops around it. Due to this magnetic field, the wire acts like a magnet which has north and south poles. Formation of magnetic north and south poles deflects the compass needle in north-south position.
Q:
The bulb in the circuit shown in Fig.14.23 does not glow. Can you identify the problem? Make necessary changes in the circuit to make the bulb glow.
A:
The bulb in the given diagram does not glow because positive sides of the cells are shown connected to each other. Rearrange the cells in a manner that negative side of one cell comes in contact with positive side of the other. By reversing the sides of cell, the circuit will complete and bulb will glow.
Q:
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)
A:
- False
- True
- False
- True
Q:
Fill in the blanks: (1) Longer line in the symbol for a cell represents its_________ terminal. (2) The combination of two or more cells is called a___________. (3) When current is switched ‘on’ in a room heater, it__________. (4) The safety device based on the heating effect of electric current is called a_______.
A:
(1) Longer line in the symbol for a cell represents its positive terminal.
(2) The combination of two or more cells is called a battery.
(3) When current is switched ‘on’ in a room heater, it produces heat.
(4) The safety device based on the heating effect of electric current is called a electric fuse.
Benefits of NCERT Solutions
1. The NCERT solutions for class 7 are prepared keeping in mind the necessary rules and format issued by the CBSE board thus providing students much-needed preview of the exam pattern of questions and preview of the exam that they are going to face during the final exams.
2. The students can be sure about the quality of the solutions as they are committed by highly experienced and expert teachers. These teachers have years of experience and they make sure that there is no mistake committed when preparing the solutions.
3. The NCERT 7 solutions are provided for the questions that are most likely to appear in the exam thus improving the efficiency of the students by helping them prepare for the important parts of the syllabus.
Tips & Strategies for Class 7 Exam Preparation
2. Organize your study time by making a timetable as it will help you manage your time accordingly.
3. Take mock tests and solve sample papers as they will help you learn time management during the exam and make you familiar with the exam pattern.
4. Take regular breaks, look after yourself by sleeping properly and eating well.
5. Know your exam well, explore the mock tests, and practice sample papers as much as you can.
Why Choose Extramarks CBSE Class 7 Study Materials?
2. The NCERT solutions for class 7 are designed in a clear and simple language complete with diagrams so that the students understand the subject well.
3. The NCERT 7 solutions are accurate thus improving their reliability.
4. The solutions are designed by expert and experienced teachers that help in removing all doubts out of the solutions and improving the credibility of the answers.
Yes, the NCERT book has been designed keeping in mind the pattern of paper that will be presented in the exam to students. The NCERT book is sufficient to study for the exam as it has everything related to the exam and contains all information out of which the questions will be asked in the exam. But if you want to prepare a little bit extra, we suggest that you go through the NCERT class 7 solutions.
When you are studying the NCERT book for math and other subjects for your class 7 exams, refer to the NCERT class 7 solutions simultaneously so you can see where you are going wrong and what are you getting right in your exercises’ attempt.
The class 7th is very crucial as it is among the major middle school classes during which the child’s base is formed in math and science and even in other subjects like English. Thus, it is students must study smartly in this class and ace their exams while getting all the help they need from the NCERT 7 solutions given by Extramarks.
Yes, absolutely. The NCERT solutions provided by Extramarks for class 7 are eloquent and elaborate at best and are thus useful for students studying for the final exams of class 7. The students will have many questions and doubts regarding the NCERT solutions for class 7 and this is why the solutions have been elaborated well to help students understand the answers to exercises.
Yes, the NCERT solutions for Math and other subjects for class 7 are available for free from Extramarks.
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