Important Questions on Magnetic Effects of Current and Magnetism for Students
FAQs on Magnetic Effects of Current and Magnetism Practice Paper
1. What is the magnetic effect of electric current?
Magnetic effect of electric current refers to the phenomenon by which an electric current flowing through a conductor produces a magnetic field around it. This is also known as electromagnetism and forms the basis of devices like electric bells, motors, and electromagnets.
- First observed by Hans Christian Oersted in 1820
- Current-carrying wires create circular magnetic fields around them
- Direction of the magnetic field can be determined by the right-hand thumb rule
- Used in applications such as generators, transformers, and electric meters
2. State the right-hand thumb rule and its significance in magnetism.
The right-hand thumb rule helps to determine the direction of the magnetic field around a current-carrying conductor. According to the rule:
- Hold the wire in your right hand with your thumb pointing in the direction of the current
- The direction in which your fingers curl represents the direction of the magnetic field around the wire
3. What are the main differences between a bar magnet and an electromagnet?
Bar magnets and electromagnets both produce magnetic fields, but differ in their origin and properties.
- Bar magnet: Permanent, natural magnet with fixed magnetism
- Electromagnet: Temporary, created by passing current through a coil, magnetism can be switched on/off
- Strength of electromagnet depends on current and coil turns; bar magnet's strength is fixed
- Electromagnets can be made much stronger for industrial and scientific uses
4. What factors affect the strength of the magnetic field produced by a current-carrying solenoid?
The magnetic field inside a current-carrying solenoid depends on:
- Number of turns: More turns per unit length increases the field strength
- Current strength: Greater electric current produces a stronger magnetic field
- Core material: Using a soft iron core intensifies the solenoid's magnetic effect
5. Explain Fleming's left-hand rule with its applications.
Fleming's left-hand rule helps predict the direction of force exerted on a current-carrying conductor in a magnetic field.
- Thumb: Direction of force
- Forefinger: Direction of magnetic field
- Middle finger: Direction of current
6. What is electromagnetic induction and who discovered it?
Electromagnetic induction is the process of generating an electric current by changing the magnetic field around a conductor. It was discovered by Michael Faraday in 1831.
- When a magnetic field around a conductor changes, an induced current is produced
- This principle is used in generators and transformers
7. Describe the construction and working of an electric motor.
An electric motor converts electrical energy into mechanical energy using the principle of the magnetic effect of current.
- Consists of a coil, magnets, commutator, and brushes
- When current passes through the coil, it experiences a force and rotates
- The commutator reverses current direction, ensuring continuous rotation
8. What is the role of a soft iron core in an electromagnetic device?
A soft iron core is used inside electromagnetic devices like solenoids to enhance the strength of the magnetic field produced by the coil.
- It concentrates and amplifies magnetic lines of force
- Improves efficiency of devices such as transformers and electromagnets
9. How can you show the existence of a magnetic field around a conductor?
The presence of a magnetic field around a current-carrying conductor can be demonstrated using iron filings or a compass needle.
- Place a straight conductor through a sheet of cardboard and sprinkle iron filings: filings arrange in concentric circles, showing the magnetic field pattern
- Moving a compass needle near a current-carrying wire makes it deflect, indicating the field's direction
10. What are the uses of electromagnets in daily life?
Electromagnets have various practical applications in daily life, taking advantage of the magnetic effect of current.
- Electric bells and buzzers
- Lifting and handling heavy metallic loads in scrap yards
- Motors, generators, and relays
- Magnetic resonance imaging (MRI) in hospitals
11. Distinguish between magnetic field and magnetic field lines.
Magnetic field is the region around a magnet or current-carrying conductor where magnetic force can be experienced, while magnetic field lines are imaginary lines that represent the direction and strength of the magnetic field.
- Field lines start from the north pole and end at the south pole of a magnet
- Their closeness indicates the strength of the field
- No two magnetic field lines intersect each other
12. Why don't two magnetic field lines intersect each other?
Two magnetic field lines never intersect because, at any point, the direction of magnetic force must be unique.
- If they intersected, it would mean two directions of the magnetic field at a single point, which is not possible






















