Overview: Magnetic Effects of Electric Current | Science Class 10 PDF Download

Magnetism

• A magnet attracts iron or iron-like substances.
• Electric currents create magnetic effects.
• Electromagnets and electric motors use the magnetic effect of electric current, while electric generators use the electric effect of moving magnets.
• Passing an electric current through a metallic conductor can deflect a compass needle.

Properties of Magnets

• Every magnet has two poles: North and South.
• Like poles repel each other, and unlike poles attract each other.
• A freely suspended bar magnet aligns itself in a nearly north-south direction with its north pole pointing north.

Characteristics of Magnetic Field Lines

• Field lines originate from the North pole and terminate at the South pole.
• Field lines are closed curves.
• Field lines are closer in a stronger magnetic field.
• Field lines never intersect.
• Inside a magnet, the field lines go from South to North.
• The degree of closeness of field lines indicates the relative strength of the magnetic field.

Magnetic Field of a Bar Magnet

• Hans Christian Oersted first stated that electric current has a magnetic field.
• Right Hand Thumb Rule determines the direction of the magnetic field around a current-carrying conductor.
• Magnetic field lines form concentric circles around a straight conductor carrying current.
• The magnetic field strength is proportional to the current and inversely proportional to the distance from the conductor.

Magnetic Field due to Current through a Circular Loop

• Magnetic field lines form concentric circles around a circular current-carrying conductor.
• The strength of the magnetic field depends on the current, distance from the conductor, and the number of turns in the coil.
• Magnetic fields of multiple loops add up because of the directions of current in each loop.

Solenoid

• A solenoid is a coil of many circular turns of insulated copper wire wound closely in a cylindrical form.
• Its magnetic field is similar to that of a bar magnet.
• The magnetic field is uniform inside the solenoid with parallel field lines.
• The direction of the magnetic field is from North to South outside the solenoid and from South to North inside.
• A solenoid can be used to magnetize magnetic materials like soft iron.

Electromagnets vs. Permanent Magnets

• Electromagnets are temporary magnets that can be easily demagnetized, while permanent magnets cannot.
• Electromagnets allow variable strength and polarity, while permanent magnets have fixed properties.

Force on a Current-Carrying Conductor in a Magnetic Field

• André-Marie Ampère suggested that a magnetic field exerts an equal and opposite force on a current-carrying conductor.
• The displacement in the conductor is maximal when the current direction is perpendicular to the magnetic field.
• The direction of force is reversed when the direction of current is reversed.
• Fleming's Left Hand Rule helps determine the direction of force.

Electric Motors

• Electric motors convert electrical energy into mechanical energy.
• They use a rotating coil of insulated copper wire in a magnetic field to generate motion.
• A split-ring commutator reverses the direction of the current and force on the coil, ensuring continuous rotation.

Electric Generator

• Electric generators convert mechanical energy into electricity.
• They use a rotating rectangular coil in a magnetic field to induce a current.
• A split-ring commutator or slip rings are used to control the direction of the induced current, leading to either direct or alternating current.
• Generators produce electrical energy.

[Question: 907242]

Domestic Electric Circuits

• Electric circuits have live (positive, red insulation), neutral (negative, black insulation), and earth (green insulation) wires.
• In India, the potential difference between live and neutral wires is 220 V.
• Safety devices include fuses, earth wires, and MCBs (Miniature Circuit Breakers) to prevent electrical accidents.