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Electric Current And Its Effects

Electric Current and Its Effects Worksheets for CBSE Class 7 Science - Free PDF 2025-26

Q: 7. What are open and closed circuits, and why is this concept fundamental to scoring well in this chapter?

An open circuit refers to an incomplete electrical path where a break (like an open switch) prevents the flow of current. A closed circuit is a complete, unbroken path that allows electric current to flow from the source, through the components, and back. This concept is fundamental because every question on electrical devices, from a simple bulb to a complex electric bell, depends on it. To analyse any circuit diagram or explain how a device works, you must first identify whether the circuit is open (off) or closed (on). This basic understanding is essential for answering almost all important questions in this chapter correctly.

Practice Important Questions and Answers on Electric Current and Its Effects for Class 7 Science 2025-26

CBSE Class 7 Science Electric Current and Its Effects Worksheets with Answers for Chapter 14 in PDF format to download prepared by expert Science teachers from the latest edition of CBSE(NCERT) books. Register Online for NCERT Solutions Class 7 Science tuition on Vedantu to score more marks in the CBSE board examination.

Worksheets are an important part of academic improvement. The easiest method to enhance and learn a chapter in greater depth is to answer questions. Make sure you're writing the solution on the worksheet as you work on it. This will not only increase your topic knowledge but also your ability to present your answers, which is crucial during an examination. MCQ and subjective questions are included in the Entrance worksheet.

Vedantu is a platform that provides free CBSE Solutions (NCERT) and other study materials for students. Maths Students who are looking for better solutions can download Class 7 Maths NCERT Solutions to help you to revise the complete syllabus and score more marks in your examinations.

Why Should One Solve Class - 7 Science Worksheets?

This Science subject in Class 7 has a variety of interesting chapters, with a few of them having numerical lines of two to three lines and the rest being theoretical. Begin by reading NCERT Chapter 1 and following the directions.

Make sure to include all significant points with a proper picture in your notes, and try to write down all important Science formulas individually.
Start practising the questions from the Class 7 Science worksheets once you've finished your chapter notes.
Do all of the questions in the textbook and make a list of essential points you notice while writing the answers to the questions in the textbook or on the worksheet.

Never miss a class in class 7 Science from your school or your tuition. If you are unable to attend the session for any reason, be sure to study the notes from the previous class.
Read the theory from your textbook right after class. NCERT textbooks are preferred. Read the theory in the NCERT textbook and try to make notes.

Topics in Chapter 14:

Electric Current and Its Effects in Class 7 Science is an essential chapter in Science. It covers the fundamentals of electronics, which are important in higher education. The key or important issues regarding chapter -14 are listed in the table below.

S.No	Topic Name
1	Symbols of Electronic Components
2	Heating effect of electric current
3	Magnetic effect of electric current
4	Electromagnet
5	Electric bell

Short Notes on Chapter -14 Electric Current and Its Effects:

Components and Their Symbols in Electronics:

An electronic component is a part of an electric circuit that facilitates its operation.
The electric circuit permits electricity to flow through it and is used to provide electricity for a variety of functions, including running electric motors, powering a lamp or fan, and producing heat.
The term "battery" refers to a collection of two or more cells. In a battery, one cell's negative terminal is linked to the next cell's positive terminal, and so on. Toys, remote controls, torches, and transistors are all devices that consume batteries.

Electric Current's Heating Effect:
A wire becomes heated when an electric current flows across it. The heating effect of electric current is what this is called. The amount of heat produced in the wire is determined by the following factors:
The wire's composition, length, and thickness are all factors to consider.
Many appliances, such as the following, rely on the heating effect of electric current.
Electric heaters, electric irons, electric stoves, geysers, electric coffee makers, toasters, and hair dryers are all examples of electric appliances.
When electricity flows through these elements, they produce a lot of heat. This quantity, however, may vary based on the device's requirements. This is because they include an element, which is a coil of wire. Various types, diameters, and lengths of wire are utilised in such appliances depending on the amount of heat required. When wires are heated, they can break down or melt.

The Heating Effect of Electric Current Causes Light to Be Produced in a Bulb:

A bulb's filament is a coiled wire that becomes heated when electricity is delivered through it. As a result, the filament glows, and light is created by the bulb.

What Exactly is an Electric Fuse?

An electric fuse is a device that protects against the damage that an excess of electric current might produce. When current is conducted through a wire, it heats up due to the heating action of the electric current. A wire, on the other hand, can melt or break if an excessive amount of electricity is sent through it.

A wire consisting of a metal or alloy with a low melting point forms the basis of the electric fuse. As a result, when a large amount of current is passed through the wire, it readily breaks down. The circuit of the fuse opens as the wire breaks, and no current travels through it. This can prevent a fire from forming owing to a short circuit caused by excessive electric current.

Electric Current's Magnetic Effect:

Electric current has a magnetic effect as it passes across a wire. Hans Christian Oersted, a scientist, discovered the magnetic effect of electric current.

When an electric current is passed through a wire positioned near the compass, the needle of the compass deflects, he discovered. This implies the needle is deflected by a magnetic field formed near the wire.

Electromagnet:

Every magnetic material has a magnetic field within which it can feel the effects of its magnetism. An electromagnet is a magnet that generates a magnetic field by using electric electricity.

Because of the magnetic influence of electric current, an electromagnet is generated.

Domestic items like electric bells employ electromagnets. They are employed in toys, in telecommunication equipment of all types, in cranes to separate magnetic materials from garbage and lift big objects, and by doctors to remove any magnetic materials that have fallen into our eyes.

Electric Bell:

The components of an electric bell are very important. The Electromagnet is made up of a coil of wire wound around an iron piece. A hammer is fastened to an iron strip (soft iron armature) that is connected to the wire coil. A contact screw that connects the iron strip to the contact screw. The wire coil and the contact screw are connected via a battery. A switch in the circuit's middle.

Class - 7 Science Worksheets:

To help you improve your grades in class, Vedantu has posted many academic resources for class 7 Science, including class 7 Science formulae, class 7 reference book solutions, and worksheets for class 7 Science. In addition, you can take a chapter-by-chapter online test for class 7 Science. Science worksheets for class 7 have been developed. Senior teachers from several schools provide solutions. To use these worksheets, you must do a few things, such as read the chapter and make sure you have reviewed the notes before attempting to solve the worksheet.

FAQs on Electric Current and Its Effects Worksheets for CBSE Class 7 Science - Free PDF 2025-26

1. What are the most important circuit symbols from the chapter Electric Current and Its Effects for the Class 7 exam?

For the CBSE Class 7 Science exam 2025-26, it is crucial to know the standard symbols for drawing circuit diagrams. These are frequently asked in 1-mark or diagram-based questions. The most important symbols include:

Electric Cell: A long line and a shorter, thicker parallel line.
Battery: A combination of two or more cells.
Switch (ON position): A closed path in the circuit line.
Switch (OFF position): A broken path in the circuit line.
Electric Bulb: A circle with a cross or a loop inside.
Wire: A simple straight line.

2. Explain the heating effect of electric current. Why is this considered a frequently asked question?

The heating effect of electric current is the phenomenon where a conductor produces heat when an electric current passes through it. This happens because the material of the conductor offers resistance to the flow of current. This is a frequently asked concept because it demonstrates the conversion of electrical energy into heat energy, a principle that underlies many common household appliances like an electric heater, iron, or geyser. Questions on this topic often test a student's understanding of real-world applications.

3. What is an electric fuse and how does it work? Why is it an important safety device?

An electric fuse is a safety device used in electrical circuits to protect appliances from damage due to excessive current. It consists of a special wire that has a very low melting point. When a dangerously high current flows through the circuit (due to a short circuit or overloading), this wire heats up, melts, and breaks the circuit. This stops the flow of electricity, preventing potential fires and damage to expensive appliances. Its role as a protector makes it a very important topic for exams.

4. How does an electromagnet differ from a permanent magnet? This comparison is important for 3-mark questions.

An electromagnet and a permanent magnet differ in several key ways, making this a common comparison question:

Nature: An electromagnet is a temporary magnet; it only behaves like a magnet when electric current flows through its coil. A permanent magnet retains its magnetic properties continuously.
Strength: The strength of an electromagnet can be increased or decreased by changing the amount of current or the number of coils. The strength of a permanent magnet is fixed.
Polarity: The North and South poles of an electromagnet can be reversed by reversing the direction of the current, which is not possible for a permanent magnet.

5. Explain the working of an electric bell with a neat diagram. Why is this often a 5-mark question?

The working of an electric bell is a high-value question as it tests multiple concepts like circuits and the magnetic effect of current. It works on the principle of an electromagnet. The steps are:
1. When the switch is pressed, the circuit is completed, and current flows through the coil, turning it into an electromagnet.
2. The electromagnet attracts the soft iron armature.
3. The hammer, attached to the armature, strikes the gong and produces a sound.
4. At the same time, the armature loses contact with the contact screw, which breaks the circuit.
5. The coil is no longer an electromagnet, and the armature springs back to its original position.
6. The armature touches the contact screw again, completing the circuit, and the cycle repeats, causing the bell to ring continuously.

6. Why does a nichrome wire get very hot in an electric heater, while the copper connecting wires do not?

This is a higher-order thinking question that tests the concept of resistance. The reason lies in their different electrical properties:

Nichrome Wire: This material has a high electrical resistance. When current flows, this high resistance causes a lot of friction for the electrons, converting a large amount of electrical energy into heat energy.
Copper Wire: This material has a very low electrical resistance. It allows electric current to pass through it easily without significant opposition, thus producing negligible heat. It is an excellent conductor, not a heating element.

7. What are open and closed circuits, and why is this concept fundamental to scoring well in this chapter?

An open circuit refers to an incomplete electrical path where a break (like an open switch) prevents the flow of current. A closed circuit is a complete, unbroken path that allows electric current to flow from the source, through the components, and back. This concept is fundamental because every question on electrical devices, from a simple bulb to a complex electric bell, depends on it. To analyse any circuit diagram or explain how a device works, you must first identify whether the circuit is open (off) or closed (on). This basic understanding is essential for answering almost all important questions in this chapter correctly.

8. What could happen if you use a fuse with a very high melting point in a domestic circuit? Is this a recommended practice?

This is a common conceptual question to test your understanding of safety. Using a fuse with a very high melting point is extremely dangerous and not recommended. A proper fuse is designed to melt and break the circuit when the current exceeds a safe limit. If the fuse wire has too high a melting point, it will not melt during an overload or short circuit. The excessive current will continue to flow, causing the appliance's wiring to overheat, which can lead to a fire or permanent damage to the appliance.