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Published on: 07/12/2018
The National Council of Education and Training sets the curriculum for all schools that follow the Central Board of Secondary Education (CBSE) across the nation. The important questions provided below will also make students familiar with the marking scheme and the difficulty level of the exam. The important questions for CBSE class 7 Science are prepared by subject experts according to the latest syllabus of CBSE. Students are advised to solve these important questions which can make them more focused on their exam and also bring a sense of discipline and seriousness in their exam preparation.
Creative questions were added in this question paper in order to enhance the student's knowledge and get the idea that how to answer strategic questions asked in the board exams. This question paper is designed based on the academic syllabus. Sample papers should be practiced in examination condition at home or school and also show it to your teachers for checking or compare with the answers provided.
The Central Board of Secondary Education (CBSE) is a prestigious educational board which comes under the Union Government of India. Here, you will get the clue that from where and how the questions are being framed from the chapter Electric Current and Effects for CBSE Class 7 Science. These questions can provide students a chapter wise preparation strategy so that they can prepare for their exam more efficiently.
Download CBSE Class 7th Standard CBSE Science question papers, sample papers, important questions, and previous year solved papers in PDF format. Get free study materials, NCERT solutions, and exam preparation resources for Class 7th Standard CBSE Science
Questions + Answers key
Take MCQ Science Test
1.
Batteries used in tractors, trucks and inverters are also made from cells. Then why it is called a battery?
2.
Boojho made an electromagnet by winding 50 turns of wire over an iron screw. Paheli also made an electromagnet by winding 100 turns over a similar iron screw. Which electromagnet will attract more pins? Give reason.
3.
If cells are placed side by side. Then, how are the terminals of the cells connected?
4.
Can we use the same fuse in a geyser and a television set? Explain.
5.
Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.
6.
One day Sohan went to his friend's house. He was surprised to see that most of the electrical appliances at his house were functional. For example tube light and fan in all rooms, two TV's, computer, light of toilet and kitchen were switched on Sohan told his friend that this is not the way to use electricity.
Now the question arises whether this habit of consuming electrical energy is acceptable or not. Why?
7.
Can we use the same fuse in geyser and a television set? Explain.
8.
Why should we not touch the lighted bulb?
9.
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.
10.
Paheli does not have a night lamp in her room. She covered the bulb of her room with a towel in the night to get dim light. Has she taken the right step? Give one reason to justify your answer.
11.
Explain the working of electric bell with diagram
12.
Last Sunday, Pulpit was playing videotape in his room. While playing, the electricity of his house went off due to which he could not able to see anything around him. Then anyhow, he managed to get his mobile in his hand and with the help of its light, he went outside of his room to check if there was any problem in the electric circuit board of his house.
At the same time, his father suggested him to maintain the distance from the circuit board and decided to call some electrician to check the problem.
(a) Explain, what happens when live wire and neutral wire touches each other directly?
(b) State the values here showed by Pulkit's father.
13.
Paheli took a wire of length 10 cm. Boojho took a wire of 5 cm of the same material and thickness both of them connected with wires as shown in the circuit given in figure. The current flowing in both the circuits is the same.
(a) Will the heat produced in both the cases be equal? Explain.
(b) Will the heat produced be the same, if the wires taken by them are of equal lengths but of different thickness? Explain.
14.
Which depends only on the heating effect of current?
Hair dryer
Room heater
CFL
Electric bulb
15.
When a switch is in OFF position,
(i) circuit starting from the positive terminal of the cell stops at the switch
(ii) circuit is open
(iii) no current flows through it
(iv) current flows after sometime
Choose the combination of correct answer from the following.
All are correct
(ii) and (iii) are correct
Only (iv) is correct
(i) and (ii) are correct
16.
Which of the following precautions need not be taken while using electric gadgets/ appliances/circuit?
We should never touch a lighted electric bulb connected to the mains
We should never do experiment with the electric supply from the mains or a generator or an inverter
We should never use just any wire or strip of metal in place of a fuse
We should never turn the switch in ON position
17.
Choose the statement which is not correct in the case of an electric fuse.
Fuses are inserted in electric circuits of all buildings
There is a maximum limit on the current which can safely flow through the electric circuits
There is a minimum limit on the current which can safely flow in the electric circuits
If a proper fuse is inserted in a circuit it will below off if current exceeds the safe limit
18.
Current does not flow in an____circuit.
19.
A combination of two or more cells is called a_____________.
20.
Our body is a_____________of electricity.
21.
Electric fuse is based on the magnetic effect of electric current.
22.
CFLs consume more electricity than an ordinary bulb.
23.
What do you mean by open circuit?
1.
The cell is the unit of battery when more than one cell are combined together, it forms a battery. In trucks, tractors and inverters, cells are internally arranged and we need not to connect it externally, so we called it as batteries.
2.
Since the magnetic effect directly depends on the number of turns of the coil. As, Paheli's coil has more number of turns than Boojho. So, her electromagnet is stronger than Boojho.
So, electromagnet of Paheli attracts more pins as compared to Boojho.
3.
If cells are placed side by side, then with the help of some connecting wires, the positive terminal of one cell is connected to the negative terminal of other to produce a combined power of all cells which can be called a battery.
4.
No, we cannot use same fuse in a geyser and in a television set because the fuse used in every appliances has some limit to withstand the current flows through it. So, different appliances have different fuses.
5.
No, an electromagnet cannot be used for separating plastic bags from a garbage heap because plastic bags are not magnetic materials. Only magnetic materials can be attracted by the magnet, so plastic bags do not get attracted by the magnet.
6.
No, it is not acceptable. It will affect the economical condition of family as well as the nation because mostly non-renewable sources of energy is used to generate large amount of electricity. We should conserve the energy.
7.
No, a geyser and a television set require different amount of current. Therefore the fuse used in these will be of different ratings.
8.
We should never touch a lighted electric bulb connected to the mains. It may be very hot and our hand may get burnt badly. In the same way, we do not experiment with the electric supply from the mains or a generator or an inverter. It may cause an electric shock.
9.
10.
No, she has not taken the right step. Because due to excessive heat of bulb, the towel may burn and it also results in the wastage of electrical energy.
11.
Electric bell consists of an iron hammer around which a wire is wound. When current is passed by pressing the button, the wire turns into a temporary magnet. The hammer is attracted towards gong to make sound. When this strikes, the current is disconnected automatically. It happens due to shift arrangement in it. The magnetic property of wire is lost and it comes back to its original position through a spring. In this way, we get separated hammering, resulting in ringing of an electric bell
12.
(a) When live and neutral wire touches each other directly then it leads to short circuit in which the large amount of current flows through the household wiring and this large current may heat the wires to a dangerously high temperature and a fire may be started.
(b) Pulkit's father seems very sensible in taking the decisions and he showed a very great concern towards his son.
13.
(a) No, the amount of heat produced in both the wires will be different because amount of heat produced in a wire on passing electric current depends on the length of wire and here length is different for both the wires.
(b) No, the amount of heat produced in the wire of same length but different thickness cannot be same because amount of heat produced in a wire also depends on the thickness of the wire.
14.
(a)
Hair dryer
15.
(d)
(i) and (ii) are correct
16.
(b)
We should never do experiment with the electric supply from the mains or a generator or an inverter
17.
(c)
There is a minimum limit on the current which can safely flow in the electric circuits
18.
( )
Open
19.
( )
battery
20.
( )
good conductor
21.
(b)
22.
(b)
23.
( )
Open circuit means switch is in off position.
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