--- title: "NCERT Solutions Class 7 Science Electricity: Circuits and their Components" url: https://www.swavid.com/science/class/7/chapter/electricity-circuits-and-their-components/ncert-solutions dateModified: 2026-10-07T16:05:06+00:00 --- # NCERT Solutions Class 7 Science Electricity: Circuits and their Components This chapter's questions cover fundamental concepts of electricity, including simple electrical circuits, cells, batteries, switches, incandescent and LED lamps, and electrical conductors versus insulators. They test students' understanding through circuit analysis, diagram drawing, and reasoning about electrical components. Free PDF (6 pages): https://www.swavid.com/api/seo/pdf/ncert/science/class-7/swavid-ncert-solutions-class-7-science-chapter-3-electricity-circuits-and-their-components-d3bbadf2aa.pdf ## Let Us Enhance Our Learning ### Question 1 *1 mark · MCQ* Choose the incorrect statement. - A switch is the source of electric current in a circuit. - A switch helps to complete or break the circuit. - A switch helps us to use electricity as per our requirement. - When the switch is in 'OFF' position, there is an air gap between its terminals. **Solution** 1. An electric cell or battery is the source of electric current in a circuit, not a switch. 2. A switch is a device that completes or breaks the circuit as per our requirement. **Answer:** (i) A switch is the source of electric current in a circuit. > Common mistake: Students often confuse the source of electricity (cell/battery) with the control device (switch). ### Question 2 *3 marks · Short answer* Observe Fig. 3.16. With which material connected between the ends A and B, the lamp will not glow? **Solution** 1. The lamp will not glow if an electrical insulator (such as wood, plastic, glass, rubber, or paper) is connected between ends A and B. 2. Insulators are materials that do not allow electric current to pass through them. 3. Since the path for the electric current remains incomplete, the lamp does not glow. **Answer:** An electrical insulator (such as wood, plastic, rubber, or glass). > Common mistake: Naming a metal or conductor instead of an insulator. ### Question 3 *3 marks · Short answer* In Fig. 3.17, if the filament of one of the lamps is broken, will the other glow? Justify your answer. **Solution** 1. No, the other lamp will not glow. 2. When the filament of one lamp is broken, the circuit becomes incomplete or breaks at that point. 3. A complete path is required for electric current to flow through the circuit, so no current reaches the other lamp. **Answer:** No, the other lamp will not glow because a broken filament creates a gap in the circuit, stopping the flow of current. > Common mistake: Thinking that electricity can jump across the gap or bypass the broken lamp in a single-loop circuit. ### Question 4 *3 marks · Short answer* A student forgot to remove the insulator covering from the connecting wires while making a circuit. If the lamp and the cell are working properly, will the lamp glow? **Solution** 1. No, the lamp will not glow. 2. Plastic and rubber coverings on connecting wires are electrical insulators. 3. The insulator covering prevents metal-to-metal contact at the terminals, keeping the circuit incomplete and preventing current from flowing. **Answer:** No, the lamp will not glow because the plastic covering acts as an insulator and prevents electric contact. > Common mistake: Assuming electricity flows even through the plastic insulation of wires. ### Question 5 *3 marks · Short answer* Draw a circuit diagram for a simple torch using symbols for electric components. **Solution** 1. Draw a rectangular or closed loop representing the connecting wires using straight lines. 2. Include the symbol for a cell or battery (alternating long and short parallel lines) and an electric lamp (circle with a cross or loop inside). 3. Add a switch symbol in either the open ('OFF') or closed ('ON') position to complete the circuit diagram. **Answer:** A circuit diagram containing a cell/battery, a switch, and a lamp connected by straight lines representing wires, similar to Fig. 3.14a in the textbook. > Common mistake: Using artistic drawings instead of standard electrical symbols from Table 3.2. ### Question 6 *3 marks · Short answer* In Fig. 3.18: (i) If $S_2$ is in 'ON' position, $S_1$ is in 'OFF' position, which lamp(s) will glow? (ii) If $S_2$ is in 'OFF' position, $S_1$ is in 'ON' position, which lamp(s) will glow? (iii) If $S_1$ and $S_2$ both are in 'ON' position, which lamp(s) will glow? (iv) If both $S_1$ and $S_2$ are in 'OFF' position, which lamp(s) will glow? **Part (i)** 1. Switch S2 is ON and switch S1 is OFF. 2. Since S1 is OFF, the main path containing S1 is broken, so no current reaches any lamp. Answer (i): None of the lamps will glow. **Part (ii)** 1. Switch S2 is OFF and switch S1 is ON. 2. The path through S2 is broken, preventing current from passing through lamp L2. Answer (ii): Only lamp L1 will glow. **Part (iii)** 1. Both S1 and S2 are in the ON position. 2. Both switches close their respective paths, completing the circuit for both lamps. Answer (iii): Both lamps L1 and L2 will glow. **Part (iv)** 1. Both S1 and S2 are in the OFF position. 2. The circuit is broken at multiple points, so no current flows. Answer (iv): None of the lamps will glow. **Answer:** Depending on the switch positions, different combinations of lamps glow as determined by whether the paths are closed. > Common mistake: Misinterpreting series and branch connections when switches are turned on or off. ### Question 7 *3 marks · Short answer* Vidyut has made the circuit as shown in Fig. 3.19. Even after closing the circuit, the lamp does not glow. What can be the possible reasons? List as many possible reasons as you can for this faulty operation. What will you do to find out why the lamp did not glow? **Solution** 1. The electric cell may be used up or dead. 2. The lamp filament may be broken, meaning the lamp is fused. 3. The connections at the terminals may be loose, or the switch materials may be non-conducting. 4. To find out, check the cell, replace the lamp, and ensure all connections are tight and complete. **Answer:** Possible reasons include a dead cell, a fused lamp, loose connections, or an open switch; verify by checking each component. > Common mistake: Forgetting that a switch made of cardboard or insulating material will not complete the circuit. ### Question 8 *3 marks · Short answer* In Fig. 3.20, in which case(s) the lamp/LED will not glow when the switch is closed? **Solution** 1. In circuit (d), the LED is connected with incorrect polarity where its positive and negative terminals do not match the battery terminals correctly. 2. Additionally, an LED requires a proper voltage or number of cells, but check the diagrams for correct polarity and switch closure. 3. In case (d), the LED will not glow because current cannot pass through the LED in that direction. **Answer:** The lamp/LED will not glow in case (d) due to incorrect connection of the LED terminals. > Common mistake: Ignoring the directional property of LEDs in electrical circuits. ### Question 9 *3 marks · Short answer* Suppose the '+' and '-' symbols cannot be read on a battery. Suggest a method to identify the two terminals of this battery. **Solution** 1. Connect a wire from one terminal of the battery to the longer wire (positive terminal) of an LED and the other terminal to the shorter wire (negative terminal). 2. If the LED glows, the terminal connected to the longer wire of the LED is the positive terminal of the battery. 3. If the LED does not glow, reverse the connections; when it glows, the positive terminal is identified. **Answer:** Use an LED circuit to test the battery; the battery terminal connected to the longer wire of the LED when it glows is the positive terminal. > Common mistake: Connecting an LED without checking its polarity. ### Question 10 *5 marks · Long answer* You are given six cells marked A, B, C, D, E, and F. Some of these are working and some are not. Design an activity to identify which of them are working. (i) List the items that you require. (ii) Write the procedure that you will follow. (iii) With the items, carry out the activity to identify the cells that are working. **Part (i)** 1. Collect an electric lamp or LED, a cell holder, and connecting wires. Answer (i): Required items: lamp, connecting wires, and a lamp holder. **Part (ii)** 1. Make a simple circuit using the lamp and connecting wires. 2. Insert each cell marked A, B, C, D, E, and F one by one into the circuit. 3. Observe whether the lamp glows for each cell. Answer (ii): Procedure: Connect each cell one by one to the lamp and observe if it glows. **Part (iii)** 1. Record the cells for which the lamp glows as working cells. 2. Record the cells for which the lamp does not glow as non-working cells. Answer (iii): Working cells are those that cause the lamp to glow in the test circuit. **Answer:** A testing circuit with a lamp or LED can be used to check each cell individually. > Common mistake: Not testing each cell independently. ### Question 11 *3 marks · Short answer* Using an LED that requires two cells in series to glow, Tanya made the circuit as shown in Fig. 3.21. Will the lamp glow? If not, draw the wires for correct connections. **Solution** 1. The lamp in Fig. 3.21 will not glow because the two cells are not connected in series properly to provide the required voltage and polarity. 2. To make the LED glow, connect the positive terminal of the two-cell battery to the longer wire (positive terminal) of the LED. 3. Connect the negative terminal of the battery to the shorter wire (negative terminal) of the LED. **Answer:** The lamp will not glow; connect the positive terminal of the battery to the longer wire of the LED and the negative terminal to the shorter wire. > Common mistake: Reversing the positive and negative terminals of the LED. ## Frequently asked questions ### How many questions are there in NCERT Solutions for Class 7 Science Chapter 3 Electricity Circuits and their Components? There are 11 questions in the Let Us Enhance Our Learning section of this chapter based on the new NCERT book for the 2026-27 session. You can find step-by-step solutions for all these questions in the free PDF available on this page only. ### Which topics are covered in the exercises of Class 7 Science Chapter 3? The questions cover important concepts like circuit diagram representation, circuits with lamps and LEDs, electric switch function, and electrical conductors and insulators. Other topics include electrical insulation in circuits, faulty electrical circuits, identifying battery terminals, and proper LED circuit connections. ### What are the question types included in the Class 7 Science Chapter 3 exercise? The exercise includes three types of questions which are long answer questions, multiple choice questions, and short answer questions. SwaVid provides detailed answers for all these question types in the free PDF on this page to help students prepare thoroughly. ### How should students write answers for full marks in Class 7 Science Chapter 3? To score full marks, students should explain concepts clearly and draw neat circuit diagrams using standard symbols where required. Referring to the structured answers in SwaVid's free PDF on this page will help students understand the correct presentation method. ### Is the free PDF for Class 7 Science Chapter 3 solutions easily accessible? Yes, the complete chapter solutions are available as a free PDF right here on this page. Students can easily download it to revise the 11 questions and strengthen their understanding of electric circuits for the 2026-27 session. ## Related pages - [Class 7 Science chapters](https://www.swavid.com/science/class/7) Solutions written by SwaVid, a personal AI tutor for Class 6 to 10 Maths and Science. Practise this chapter free: https://www.swavid.com/start/student