Class 10 Chapter 2 Magnetic Effect of Electric Current Physics Solution S.Chand. Part 2 and 3

 Part 2 Page 81

Very Short Answer Type Questions

  1. 1.Which effect of current can be utilized in detecting a current-carrying wire concealed in a wall?
    The effect of a current-carrying wire on a nearby magnetic compass needle can be utilized in detecting the wire concealed in a wall.

  2. 2.What conclusion do you get from the observation that a current-carrying wire deflects a compass needle placed near it?
    The observation suggests that an electric current produces a magnetic field around it.

  3. 3.Name the scientist who discovered the magnetic effect of current.
    Hans Christian Ørsted.

  4. 4.State qualitatively the effect of inserting an iron core into a current-carrying solenoid.
    Inserting an iron core into a current-carrying solenoid enhances the magnetic effect, resulting in a stronger overall magnetic field.

  5. 5.Name the rule for finding the direction of magnetic field produced by a straight current-carrying conductor.
    The Right-Hand Rule.

  6. 6.State the form of magnetic field lines around a straight current-carrying conductor.
    The magnetic field lines around a straight current-carrying conductor form concentric circles perpendicular to the direction of the current flow.

  7. 7.What is the other name of Maxwell’s right-hand thumb rule?
    The Right-Hand Grip Rule.

  8. 8.State whether the following statement is true or false: The magnetic field inside a long circular coil carrying current will be parallel straight lines.
    False. The magnetic field inside a long circular coil carrying current will not be parallel straight lines. Instead, it will resemble the magnetic field lines of a bar magnet, curving around inside the coil.

  9. 9.What is the shape of a current-carrying conductor whose magnetic field pattern resembles that of a bar magnet?
    A solenoid.

  10. 10.State three ways in which the strength of an electromagnet can be increased.

  • Increasing the number of turns in the coil (increasing the number of loops).
  • Increasing the current flowing through the coil.
  • Inserting a ferromagnetic material (such as iron) into the core of the coil to enhance its magnetic properties.

11. Fill in the following blanks with suitable words :

(a) The lines of magnetic field round a straight current-carrying conductor are in the shape of concentric circles. (b) For a current-carrying solenoid, the magnetic field is like that of a bar magnet. (c) The magnetic effect of a coil can be increased by increasing the number of turns, increasing the current, or inserting an iron core. (d) If a coil is viewed from one end and the current flows in an anticlockwise direction, then this end is a north pole. (e) If a coil is viewed from one end, and the current flows in a clockwise direction, then this end is a south pole.


Short Answer Type Questions

12. Describe how you will locate a current-carrying wire concealed in a wall. 

To locate a current-carrying wire concealed in a wall, one can use a magnetic field detector or a compass. Move the detector or compass along the surface of the wall perpendicular to it. When the detector or compass needle deflects, it indicates the presence and direction of the current-carrying wire behind the wall.

13. Describe some experiment to show that the magnetic field is associated with an electric current. 

One experiment involves passing an electric current through a straight wire and observing the deflection of a nearby compass needle. Another experiment is to coil the wire into a solenoid and observe the magnetic effect inside the coil using iron filings or a compass. Additionally, using a current-carrying wire to deflect a magnetic needle in a Galvanometer also demonstrates the association between electric current and magnetic field.

14. (a) Draw a sketch to show the magnetic lines of force due to a current-carrying straight conductor. (b) Name and state the rule to determine the direction of magnetic field around a straight current-carrying conductor. 

  1. (a) Draw a sketch to show the magnetic lines of force due to a current-carrying straight conductor.


    (b) The rule to determine the direction of magnetic field around a straight current-carrying conductor is the Right-Hand Rule. Point your thumb in the direction of the current flow, and your curled fingers indicate the direction of the magnetic field lines.

15. State and explain Maxwell’s right-hand thumb rule. 

Maxwell’s right-hand thumb rule is used to determine the direction of the magnetic field around a current-carrying conductor. When the right hand is used with the thumb pointing in the direction of the current, the curled fingers indicate the direction of the magnetic field lines.

16. What is Maxwell’s corkscrew rule ? For what purpose is it used ? 

Maxwell’s corkscrew rule is another method to determine the direction of the magnetic field around a current-carrying conductor. It states that if a right-handed corkscrew is turned in the direction of the current flow, then the direction in which the corkscrew moves indicates the direction of the magnetic field lines. It is used for visualizing the direction of the magnetic field around the conductor.

17. (a) Draw the magnetic lines of force due to a circular wire carrying current. (b) What are the various ways in which the strength of magnetic field produced by a current-carrying circular coil can be increased ? 

(a) Draw the magnetic lines of force due to a circular wire carrying current.

(b) The strength of the magnetic field produced by a current-carrying circular coil can be increased by increasing the current flowing through the coil, increasing the number of turns in the coil, or inserting a ferromagnetic material (such as iron) into the core of the coil to enhance its magnetic properties.

18. State and explain the Clock face rule for determining the polarities of a circular wire carrying current. 
The Clock face rule is a mnemonic used to determine the direction of the magnetic field around a circular wire carrying current. It states that if you imagine looking down at the circular wire as if it were the face of a clock, with the current flowing clockwise, then the magnetic field lines circulate around the wire in the direction that your fingers would curl if you wrap them around the wire in the direction of the current flow. This rule helps in determining the direction of the magnetic field produced by the current in the wire.

19. Name any two factors on which the strength of magnetic field produced by a current-carrying solenoid depends. How does it depend on these factors ?
  2. Two factors on which the strength of the magnetic field produced by a current-carrying solenoid depends are:

    3. a. Number of turns in the solenoid coil: The more turns of wire in the solenoid, the stronger the magnetic field produced. This is because each turn of wire contributes to the overall magnetic field strength, and having more turns increases the cumulative effect.

    b. Current flowing through the solenoid: The strength of the magnetic field is directly proportional to the current flowing through the solenoid. Increasing the current increases the strength of the magnetic field, as stated by Ampère's law.

    The strength of the magnetic field produced by a solenoid depends on these factors because both the number of turns and the current contribute to the magnetic flux density (magnetic field strength) according to the formula B = μ₀ * (n * I), where B is the magnetic flux density, μ₀ is the permeability of free space, n is the number of turns per unit length, and I is the current. Increasing either the number of turns or the current will increase the magnetic field strength accordingly.

  3. 20. (a) Draw a circuit diagram to show how a soft iron piece can be transformed into an electromagnet. (b) Describe how an electromagnet could be used to separate copper from iron in a scrap yard.

  4. (a) Here's a circuit diagram showing how a soft iron piece can be transformed into an electromagnet:


  5. (b) An electromagnet can be used to separate copper from iron in a scrap yard by utilizing the magnetic properties of both materials. When a current flows through the electromagnet, it becomes magnetized. Since iron is magnetic, it will be attracted to the electromagnet, allowing it to be separated from the non-magnetic copper. This process can be automated by using conveyor belts to carry the scrap material over the electromagnet, where the iron pieces will be attracted and separated from the copper.

  6. 21. (a) How does an electromagnet differ from a permanent magnet ? (b) Name two devices in which electromagnets are used and two devices where permanent magnets are used.

    1. (a) An electromagnet differs from a permanent magnet in that it only exhibits magnetism when an electric current is passed through it. When the current is switched off, the electromagnet loses its magnetism. In contrast, a permanent magnet retains its magnetism without the need for an external electric current.

    (b) Devices in which electromagnets are used:

    1. Electric doorbells.
    2. MRI (Magnetic Resonance Imaging) machines.

    Devices in which permanent magnets are used:

    1. Refrigerator door magnets.
    2. Loudspeakers.

 Long Answer Type Questions

22. (a) What is a solenoid ? Draw a sketch to show the magnetic field pattern produced by a current-carrying solenoid. (b) Name the type of magnet with which the magnetic field pattern of a current-carrying solenoid resembles. (c) What is the shape of field lines inside a current-carrying solenoid ? What does the pattern of field lines inside a current-carrying solenoid indicate ? (d) List three ways in which the magnetic field strength of a current-carrying solenoid can be increased ? (e) What type of core should be put inside a current-carrying solenoid to make an electromagnet ?

(a) Solenoid: A solenoid is a coil of wire wound in the form of a helix. When an electric current flows through the solenoid, it creates a magnetic field around it.

Sketch of magnetic field pattern produced by a current-carrying solenoid:



(b) The magnetic field pattern of a current-carrying solenoid resembles that of a bar magnet.

(c) Inside a current-carrying solenoid, the shape of the magnetic field lines is uniform and parallel to the axis of the solenoid. The pattern of field lines inside a current-carrying solenoid indicates a strong and uniform magnetic field along its axis.

(d) Three ways to increase the magnetic field strength of a current-carrying solenoid are:

  1. Increase the number of turns of wire in the solenoid coil.
  2. Increase the current flowing through the solenoid.
  3. Use a material with higher magnetic permeability as the core inside the solenoid.

(e) To make an electromagnet, a ferromagnetic material such as iron or steel should be put inside a current-carrying solenoid as the core.

23. (a) What is an electromagnet ? Describe the construction and working of an electromagnet with the help of a labelled diagram. (b) Explain why, an electromagnet is called a temporary magnet. (c) Explain why, the core of an electromagnet should be of soft iron and not of steel.(d) State the factors on which the strength of an electromagnet depends. How does it depend on these factors ?

(e) Write some of the important uses of electromagnets.

(a) Electromagnet: An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. It consists of a coil of wire (solenoid) wound around a core material.

Construction and Working: An electromagnet is constructed by winding a coil of insulated wire around a soft iron core. When an electric current is passed through the coil, it creates a magnetic field around the core, turning it into a magnet. The magnetic field strength can be controlled by varying the amount of current flowing through the coil or by changing the number of turns in the coil.

Labelled Diagram:

___________ +___________| |______________+ | | | | | Battery | Coil | Soft | Iron Core |___________|___________|_______|______| | | | | | | | | | | | | +___________|___________|______________- |___________|


(b) An electromagnet is called a temporary magnet because its magnetism is only present when an electric current is passing through it. When the current is turned off, the magnetic field collapses, and the electromagnet loses its magnetism.

(c) The core of an electromagnet should be made of soft iron and not steel because soft iron has high magnetic permeability, which means it can easily magnetize and demagnetize in response to changes in the electric current. Steel has lower magnetic permeability and retains magnetism even after the current is turned off, making it unsuitable for electromagnet cores.

(d) The strength of an electromagnet depends on several factors:

  1. Number of turns in the coil: More turns increase the magnetic field strength.
  2. Current flowing through the coil: Higher current produces a stronger magnetic field.
  3. Nature of the core material: Soft iron core increases magnetic field strength due to high permeability.

(e) Important uses of electromagnets include:

  1. Electric relays.
  2. Electric motors.
  3. Magnetic resonance imaging (MRI) machines.
  4. Particle accelerators.
  5. Magnetic separators.
  6. Speakers and headphones.
  7. Magnetic levitation trains.

Multiple Choice Questions (MCQs)

24. The strength of the magnetic field between the poles of an electromagnet would be unchanged if : (a) current in the electromagnet winding were doubled (b) direction of current in electromagnet winding were reversed (c) distance between the poles of electromagnet were doubled (d) material of the core of electromagnet were changed 

25. The diagram given below represents magnetic field caused by a current-carrying conductor which is :


(a) a long straight wire (b) a circular coil (c) a solenoid (d) a short straight wire 

26. 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. 

27. 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 centred on the wire. 

28. The north-south polarities of an electromagnet can be found easily by using : (a) Fleming’s right-hand rule (b) Fleming’s left-hand rule (c) Clock face rule (d) Left-hand thumb rule 

29. The direction of current in the coil at one end of an electromagnet is clockwise. This end of the electromagnet will be : (a) north pole (b) east pole (c) south pole (d) west pole 

30. If the direction of electric current in a solenoid when viewed from a particular end is anticlockwise, then this end of solenoid will be : (a) west pole (b) south pole (c) north pole (d) east pole

31. The most suitable material for making the core of an electromagnet is : (a) soft iron (b) brass (c) aluminium (d) steel

32. The magnetic effect of current was discovered by : (a) Maxwell (b) Fleming (c) Oersted (d) Faraday 

33. A soft iron bar is inserted inside a current-carrying solenoid. The magnetic field inside the solenoid : (a) will decrease (b) will increase (c) will become zero (d) will remain the same 

34. The magnetic field lines in the middle of the current-carrying solenoid are : (a) circles (b) spirals (c) parallel to the axis of the tube (d) perpendicular to the axis of the tube 

35. The front face of a circular wire carrying current behaves like a north pole. The direction of current in this face of the circular wire is : (a) clockwise (b) downwards (c) anticlockwise (d) upwards

36. The back face of a circular loop of wire is found to be south magnetic pole. The direction of current in this face of the circular loop of wire will be : (a) towards south (b) clockwise (c) anticlockwise (d) towards north

 Questions Based on High Order Thinking Skills (HOTS)

37. In the straight wire A, current is flowing in the vertically downward direction whereas in wire B the current is flowing in the vertically upward direction. What is the direction of magnetic field : (a) in wire A ? (b) in wire B ? Name the rule which you have used to get the answer

(a) In wire A, the direction of the magnetic field would be around the wire in the counterclockwise direction when viewed from above.

(b) In wire B, the direction of the magnetic field would be around the wire in the clockwise direction when viewed from above.

The rule used to determine the direction of the magnetic field around a current-carrying wire is the right-hand thumb rule.

38. The figure shows a solenoid wound on a core of soft iron. Will the end A be a N pole or S pole when the current flows in the direction shown ?

S-pole

39. A current-carrying straight wire is held in exactly vertical position. If the current passes through this wire in the vertically upward direction, what is the direction of magnetic field produced by it ? Name the rule used to find out the direction of magnetic field

When the current passes through the wire in the vertically upward direction, the magnetic field produced by it will form concentric circles around the wire, with the magnetic field lines circulating counterclockwise when viewed from above.

The rule used to find out the direction of the magnetic field around a current-carrying wire is the right-hand grip rule.

40. For the coil in the diagram below, when the switch is pressed : (a) what is the polarity of end A ? (b) which way will the compass point then ?

(a) S-pole (b) Away from the end B  (Because end B is a N pole)

41. A current flows downwards in a wire that passes vertically through a table top. Will the magnetic field lines around it go clockwise or anticlockwise when viewed from above the table ?

The magnetic field lines around the wire will go counterclockwise when viewed from above the table.

42. The directions of current flowing in the coil of an electromagnet at its two ends X and Y are as shown below :



(a) What is the polarity of end X ? (b) What is the polarity of end Y ? (c) Name and state the rule which you have used to determine the polarities.

(a) S-pole (b) N-pole (c) Clock-face rule

43. The magnetic field associated with a current-carrying straight conductor is in anticlockwise direction. If the conductor was held along the east-west direction, what will be the direction of current through it ? Name and state the rule applied to determine the direction of current ?

If the magnetic field associated with a current-carrying straight conductor is in the anticlockwise direction when viewed from above, the direction of current through it would be from south to north.

The rule used to determine the direction of current is the right-hand grip rule.

44. A current-carrying conductor is held in exactly vertical direction. In order to produce a clockwise magnetic field around the conductor, the current should be passed in the conductor : (a) from top towards bottom (b) from left towards right (c) from bottom towards top (d) from right towards left

To produce a clockwise magnetic field around the vertically held conductor, the current should be passed in the conductor from bottom towards top. 45. A thick wire is hanging from a wooden table. An anticlockwise magnetic field is to be produced around the wire by passing current through this wire by using a battery. Which terminal of the battery should be connected to the : (a) top end of wire ? (b) bottom end of wire ? Give reason for your choice

(a) To produce an anticlockwise magnetic field around the top end of the wire, the positive terminal of the battery should be connected to the top end of the wire.

(b) To produce an anticlockwise magnetic field around the bottom end of the wire, the negative terminal of the battery should be connected to the bottom end of the wire.

The reason for this choice is based on the right-hand grip rule. When current flows from the positive terminal of the battery to the negative terminal (conventional current flow), the magnetic field lines produced around the wire follow the direction of the curled fingers of the right hand when the thumb points in the direction of current flow.


 Part 3 Page 85

Very Short Answer Type Questions

1. What produces magnetism in the human body ? 

Magnetism in the human body is produced by the movement of electrically charged particles, particularly ions and electrons, within tissues and cells.

2. Name one medical technique which is based on magnetism produced in human body. For what purpose is this technique used ? 

One medical technique based on the magnetism produced in the human body is Magnetic Resonance Imaging (MRI). This technique is used to create detailed images of the internal structures of the body, including organs, muscles, and tissues, for diagnostic purposes.

3. Name two human body organs where magnetism produced is significant. 

Two human body organs where the magnetism produced is significant are the brain and the heart. In the brain, neural activity generates weak magnetic fields that can be detected by specialized equipment. Similarly, the heart's rhythmic contractions also produce detectable magnetic fields.

4. What is the full form of MRI ? 

MRI stands for Magnetic Resonance Imaging.

5. Name the technique by which doctors can produce pictures showing insides of the human body. 

The technique by which doctors can produce pictures showing the insides of the human body is Magnetic Resonance Imaging (MRI).

6. Name one technique which can detect cancerous tissue inside the body of a person.

One technique that can detect cancerous tissue inside the body of a person is Positron Emission Tomography (PET) scan.

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