Revision: Magnetic Effects of Electric Current Science English Medium Class 10 CBSE

A current-carrying conductor is always associated with a magnetic field around it is called the magnetic effect of current. It was first discovered by Hans Christian Oersted in 1820.

If a current-carrying straight conductor is held in the right hand such that the thumb points in the direction of the electric current, then the fingers curled around the conductor show the direction of the magnetic field.
This is called the Right-Hand Thumb Rule.

OR

If you hold a current-carrying conductor in your right hand with the thumb pointing in the direction of the current, then the curled fingers show the direction of the magnetic field (lines of force) around the conductor.

If a conducting wire is wound in form of a cylindrical coil whose diameter is less in comparison to its length, the coil is called a solenoid.

OR

A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is called a solenoid.

OR

When a copper wire with a resistive coating is wound in a chain of loops (like a spring), it is called solenoid.

If the forefinger, middle finger, and thumb of the left hand are stretched mutually perpendicular to each other, with the forefinger indicating the direction of the magnetic field, the middle finger the direction of current, then the thumb gives the direction of the force (motion) on the conductor.
This is called Fleming’s Left-Hand Rule.

OR

If the thumb, index finger, and middle finger of the left hand are stretched perpendicular to each other, and:

• The index finger points in the direction of the magnetic field,
• Middle finger in the direction of the current,
• Then the thumb gives the direction of the force (motion) on the conductor.

\[\vec{F}=I\vec{l}\times\vec{B}\]

• Electric current creates a magnetic field, shown by compass needle deflection.
• Oersted discovered the link between electricity and magnetism in 1820.
• Reversing current changes the direction of the magnetic field.
• Iron filings form circular patterns, showing magnetic field lines around the wire.
• Magnetic field strength increases with current and decreases with distance.

• A current-carrying conductor placed in a magnetic field experiences a force when the direction of current is not parallel to the magnetic field.
• The direction of force reverses when the direction of current or the direction of magnetic field is reversed, and no force acts when current flows parallel to the magnetic field.

• Live (red), neutral (black), and earth (green) wires are used in homes; the earth wire prevents electric shock.
• Fuses protect circuits by melting when too much current flows, stopping damage from overloading or short circuits.
• Appliances are connected in parallel so each gets equal voltage and works independently.