NCERT Solutions Class 10th Science Chapter – 12 Magnetic Effects of Electric Current
| Textbook | NCERT |
| Class | 10th |
| Subject | Science |
| Chapter | 12th |
| Chapter Name | Magnetic Effects of Electric Current |
| Category | Class 10th Science |
| Medium | English |
| Source | Last Doubt |
| NCERT Solutions Class 10th Science Chapter – 12 Magnetic Effects of Electric Current Question & Answer In This Chapter we will learn about What is SI unit of current, What is current formula, What is the unit of 1 ampere, What is unit of power, What is 1 ampere, Which is called current, What is Q in physics, What is the symbol for current, How many units is 1kV?What are the 4 units of power, What is 1 unit of power class 10, What are the 2 types of electric current, Is current AC or DC, Why is electric current called, How much is 1 watt, How much watt is 1 unit, What is 1 unit watt in India, Which is better AC or DC, Is a house AC or DC, Is a battery AC or DC, How long is 1 watt, How much light is 1 watt and more such things for more knowledge about this Chapters read their. |
NCERT Solutions Class 10th Science Chapter – 12 Magnetic Effects of Electric Current
Chapter – 12
Magnetic Effects of Electric Current
Question & Answer
| Page No. 196 |
| 1. Why does a compass needle get deflected when brought near a bar magnet? Answer – The compass needle is a small magnet. When the compass needle is brought close to a bar magnet, the magnetic field lines of the compass needle interact with the magnetic field lines of bar magnet, which causes the compass needle to deflect. |
| Page No. 200 |
| 1. Draw magnetic field lines around a bar magnet. Answer – Magnetic field lines of a bar magnet emerge from the North Pole and terminate at the South Pole as shown in the figure below.  |
| 2. List the properties of magnetic field lines. Answer – The properties of magnetic field lines are as follows – Magnetic field lines do not intersect with each other. They emerge from the North Pole and terminate at the South Pole. Inside the magnet, the direction of the field lines is from the South Pole to the North Pole. |
| 3. Why don’t two magnetic field lines intersect each other? Answer – If two magnetic field lines intersect then at the point of intersection the compass needle shows two different directions, which is not possible, hence they do not intersect with each other. |
| Page No. 201-202 |
| 1. Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop. Answer –  For the downward direction of the current, the direction of the magnetic field will be as if emerging from the table outside the loop and merging with the table inside the loop. Similarly, for current flowing in an upward direction, the direction of the magnetic field will be as if they are emerging from the table outside the loop and merging with the table inside the loop, as shown in the figure. |
| 2. The magnetic field in a given region is uniform. Draw a diagram to represent it. Answer –  |
| 3. Choose the correct option. The magnetic field inside a long straight solenoid-carrying current a. is zero. b. decreases as we move towards its end. c. increases as we move towards its end. d. is the same at all points. Answer – (d) is the same at all points The magnetic field inside a long straight current carrying solenoid is uniform therefore it is the same at all points. |
| Page No. 203-204 |
| 1. Which of the following property of a proton can change while it moves freely in a magnetic field? (There may be more than one correct answer.) a. Mass b. Speed c. Velocity d. Momentum Answer – (c) and (d) When a proton enters the region of magnetic field, it experiences magnetic force. Due to which the path of the proton becomes circular. As a result, the velocity and the momentum change. |
| 2. In Activity 12.7, how do we think the displacement of rod AB will be affected if (i) current in rod AB is increased; (ii) a stronger horse-shoe magnet is used; and (iii) length of the rod AB is increased? Answer – A current carrying conductor when placed in a magnetic field experiences force. The magnitude of this force will increase with the increase in the amount of current, length of conductor and the strength of the magnetic field. Hence, the strength of the magnetic force exerted on the rod AB and its displacement will increase if 1. The current in rod AB is increased 2. Stronger horse shoe magnet is used 3. When the length of the rod AB increases |
| 3. A positively-charged particle (alpha-particle) projected towards the west is deflected towards north by a magnetic field. The direction of magnetic field is a. Towards south b. Towards east c. Downward d. Upward Answer – Upward |
| Page No. 205 |
| 1. Name two safety measures commonly used in electric circuits and appliances. Answer – The safety measured commonly used in electric circuits are as follows- Fuse – Each circuit should be connected to a fuse because a fuse prevents the flow of excessive current through the circuit. When the current in the circuit exceeds the maximum limit of the fuse element, the fuse melts to stop the flow of current protecting the appliance connected to circuit. Earthing – Earthing protects the user from electric shocks. Any leakage of current in an appliance is transferred to the ground by earthing and the people using the appliance is prevented from getting electrocuted. |
| 2. An electric oven of 2 kW power rating is operated in a domestic electric circuit (220 V) that has a current rating of 5 A. What result do you expect? Explain. Answer – The current drawn by the electric oven can be calculated using the formula P = V × I I = P/V Substituting the values, we get I = 2000 W/220 V = 9.09 A The current drawn by the electric oven is 9.09 A which exceeds the safe limit of the circuit. This causes the fuse to melt and break the circuit. |
| 3. What precaution should be taken to avoid the overloading of domestic electric circuits? Answer – A few of the precautions to be taken to avoid the overloading of domestic electric circuits are as follows- • Connecting too many devices to a single socket should be avoided • Using too many appliances at the same time should be avoided • Faulty appliances should not be connected to the circuit |
| Exercise Question Page No. 207 |
| 1. Which of the following correctly describes the magnetic field near a long straight wire? a. The field consists of straight lines perpendicular to the wire. b. The field consists of straight lines parallel to the wire. c. The field consists of radial lines originating from the wire. d. The field consists of concentric circles centered on the wire. Answer – (d) The field consists of concentric circles centered on the wire. The magnetic field near a long straight wire are concentric circles. Their centers lie on the wire. |
| 2. At the time of short circuit, the current in the circuit a. Reduces Substantially. b. Does Not Change. c. Increases Heavily. d. Vary Continuously. Answer – (c) Increases Heavily When two naked wires in the circuit come in contact with each other, the amount of current flowing in the circuit increase abruptly resulting in short circuit. |
| 3. State whether the following statements are true or false. (a) The field at the center of a long circular coil carrying current will be parallel straight lines. (b) A wire with a green insulation is usually the live wire of an electric supply. Answer – (a) True – A long circular coil is a solenoid. The magnetic field lines inside a solenoid are parallel straight lines. (b) False – Live wires have red insulation cover while the earth wire has green insulation. |
| 4. List two methods of producing magnetic fields. Answer – Following are the methods of producing magnetic fields- • By using a permanent magnet we can produce magnetic field and it can be visualized by spreading iron fillings on a white paper and keeping a magnet beneath the paper. • A current carrying straight conductor produces magnetic field. • Different types of conductors such as solenoid and circular loop can be used to see the presence of magnetic field. |
| 5. When is the force experienced by a current–carrying conductor placed in a magnetic field largest? Answer – When the direction of the current is perpendicular to the direction of the magnetic field is when the force experienced is the largest. |
| 6. Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of magnetic field? Answer – The direction of the magnetic field can be determined using the Fleming’s Left hand rule. The direction of the magnetic field will be perpendicular to the direction of current and the direction of deflection, i.e., either upward or downward. The direction of the current is from the front wall to the back wall because negatively charged electrons move from the back wall to the front wall. The directed of the magnetic force is rightward. Hence, using Fleming’s left hand rule it can be concluded that the direction of the magnetic field inside the chamber is downward. |
| 7. State the rule to determine the direction of a (i) magnetic field produced around a straight conductor-carrying current, (ii) force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it, and (iii) current induced in a coil due to its rotation in a magnetic field. Answer – (i) The rule used to determine the direction of the magnetic field produced around a straight conductor-carrying current is the Maxwell’s right hand thumb rule. (ii) The rule used to determine the force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it is the Fleming’s left hand rule. (iii) The rule used to determine the current induced in a coil due to its rotation in a magnetic field is the Fleming’s right-hand rule. |
| 8. When does an electric short circuit occur? Answer – Listed below are two instances of when a short-circuit can occur- (1) When too many appliances are connected to a single socket or when high power rating appliances are connected to a light circuit, the resistance of the circuit becomes low as a result the current flowing through the circuit becomes very high. This condition results in a short-circuit. (2) When live wires whose insulation have worn off come in contact with each other, the current flowing in the circuit increases abruptly which results in a short circuit. |
| 9. What is the function of an earth wire? Why is it necessary to earth metallic appliances? Answer – The metallic body of electric appliances is earthed by means of earth wire. Any leakage of electric wire is transferred to the ground by means of earth wire. This prevents the user of the electric appliance from getting electric shocks. This is the reason why it is important for the metallic appliances to be earthed. |
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