NCERT Solutions for Class 10 Science Chapter 12 Magnetic Effects of Electric Current
NCERT Solutions for Class 10 Science Chapter 12 Magnetic Effects of Electric Current covers magnetic field lines, magnetic field due to current-carrying conductors, solenoid properties, Fleming's Left-Hand Rule, force on current conductors, and domestic circuit safety devices.
Overview of Topics & Subtopics (Click to Jump)
1. Magnetic Field and Field Lines
Short Note:
• Magnetic Field: The region surrounding a magnet where its magnetic force can be experienced by other magnets or magnetic substances.
• Properties of Field Lines:
1. Emerge from the North pole and enter at the South pole outside a magnet; travel South to North inside.
2. Field lines form continuous, closed loops.
3. Degree of closeness of lines indicates strength of the magnetic field.
4. Two magnetic field lines never intersect because a compass needle cannot point in two different directions at one point.
2. Field due to a Current-Carrying Conductor & Solenoid
Short Note:
• Right-Hand Thumb Rule: Imagine holding a current-carrying conductor in your right hand with the thumb pointing in the direction of current; your curled fingers point in the direction of the magnetic field lines.
• Straight Wire: Magnetic field lines are concentric circles around the wire.
• Solenoid: A long coil of many circular turns of insulated copper wire. The magnetic field inside a uniform solenoid is uniform and resembles that of a bar magnet.
• Electromagnet: Formed when a soft iron core is placed inside a current-carrying solenoid.
3. Force on a Conductor in a Magnetic Field & Fleming's Left-Hand Rule
Short Note:
• A current-carrying conductor experiences a mechanical force when placed in a magnetic field.
• The force is maximum when the direction of current is perpendicular (at 90 degrees) to the magnetic field.
• Fleming's Left-Hand Rule: Stretch the thumb, forefinger, and middle finger of your left hand mutually perpendicular to each other:
- Forefinger: Magnetic Field
- Middle Finger: Electric Current
- Thumb: Direction of Motion / Force on the conductor.
4. Domestic Electric Circuits & Safety Features
Short Note:
• Wires in Supply: Live Wire (Red insulation, 220 V), Neutral Wire (Black insulation, 0 V), Earth Wire (Green insulation, safety grounding).
• Earth Wire: Provides a low-resistance conducting path for leakage currents, protecting users from severe electric shocks.
• Short Circuiting: Occurs when live and neutral wires come in direct contact due to damaged insulation, causing an abrupt increase in current.
• Overloading: Occurs when too many electrical appliances are connected to a single socket simultaneously.
• Electric Fuse: A safety device made of a low melting point alloy that melts and breaks the circuit during high current surges.
Intext Questions - Page Number: 224
Intext Questions - Page Number: 228
1. They originate at the North pole and terminate at the South pole outside the magnet.
2. They are continuous closed curves.
3. Closer field lines indicate a stronger magnetic field.
4. No two magnetic field lines ever cross or intersect each other.
Intext Questions - Page Number: 231
Textbook Chapter End Exercise Questions
(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.
Correct Answer: (d) The field consists of concentric circles centred on the wire.
(a) the process of charging a body.
(b) the process of generating magnetic field due to a current passing through a coil.
(c) producing induced current in a coil due to relative motion between a magnet and the coil.
(d) the process of rotating a coil of an electric motor.
Correct Answer: (c) producing induced current in a coil due to relative motion between a magnet and the coil.
Read More & Chapter Resources
These short notes are designed for quick revision. Read the main points once, then use the related material below to practise the same chapter. Revising a concept and checking it with questions can make your preparation more focused.