Plastic bags are not magnetic substances and thus, electromagnets cannot be used for separating them from garbage heap.
Yes, compass needle will show deflection when switch is closed in the given circuit.
The two effects of electric current are as follows:
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:
The electrical components and their relation with each other shown above can be represented by following circuit diagram:
(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.
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.
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.
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.
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.
(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.
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.