Important Question Magnetic Effects of Electric Current Chapter 12 Science Class 10 CBSE Board

Short Questions Answer

1. Who discovered the magnetic effect of electric current?
Answer: Hans Christian Oersted discovered it in 1820.

2. What happens when an electric current passes through a conductor?
Answer: It produces a magnetic field around the conductor.

3. What do magnetic field lines represent?
Answer: They represent the direction and strength of the magnetic field.

4. What is the direction of magnetic field lines inside a bar magnet?
Answer: From the south pole to the north pole.

5. What rule helps find the direction of magnetic field around a straight current-carrying conductor?
Answer: Right-hand thumb rule.

6. What is a solenoid?
Answer: A coil of many circular turns of insulated copper wire wrapped in a cylindrical shape.

7. What type of magnetic field is produced inside a solenoid?
Answer: A uniform magnetic field.

8. What is an electromagnet?
Answer: A temporary magnet formed when a soft iron core is placed inside a current-carrying solenoid.

9. What rule determines the direction of force on a current-carrying conductor in a magnetic field?
Answer: Fleming’s left-hand rule.

10. What is the function of a fuse in an electric circuit?
Answer: It prevents damage due to overloading or short-circuiting by melting and breaking the circuit.

11. What is the potential difference between the live and neutral wire in India?
Answer: 220 volts.

12. What is the color of live, neutral, and earth wires?
Answer: Live – Red, Neutral – Black, Earth – Green.

13. What happens to the magnetic field strength when current increases in a wire?
Answer: The magnetic field strength increases.

14. What kind of field lines are obtained in a uniform magnetic field?
Answer: Parallel and equally spaced straight lines.

15. What safety measure prevents electric shock from metallic appliances?
Answer: Earthing.

Long Questions Answer

1. Explain the concept of magnetic field and magnetic field lines.
Answer: The region around a magnet where its magnetic influence is experienced is called the magnetic field. Magnetic field lines are imaginary lines that represent this field. They emerge from the north pole and enter the south pole. The closeness of lines shows the field’s strength, and they never intersect each other.

2. Describe an activity to show that current-carrying conductors produce magnetic fields.
Answer:

• Take a copper wire connected in a circuit with a battery and switch.
• Place a compass near the wire.
• When current flows, the compass needle deflects, showing that the wire produces a magnetic field.
  This proves that an electric current has a magnetic effect.

3. State and explain the right-hand thumb rule.
Answer: If a current-carrying conductor is held in the right hand such that the thumb points in the direction of current, the curled fingers show the direction of the magnetic field around the conductor.
This rule helps determine the field direction in straight and circular conductors.

4. What is a solenoid? Describe its magnetic field and uses.
Answer: A solenoid is a coil of many circular turns of insulated wire wound closely in a cylindrical form. The magnetic field inside it is uniform and similar to that of a bar magnet, with one end behaving as the north pole and the other as the south.
Uses: It is used to make electromagnets and in devices like electric bells.

5. Explain Fleming’s Left-Hand Rule with the help of a diagram.
Answer: If the thumb, forefinger, and middle finger of the left hand are stretched mutually perpendicular:

• Forefinger → Direction of magnetic field
• Middle finger → Direction of current
• Thumb → Direction of motion or force
  This rule helps find the direction of force on a current-carrying conductor in a magnetic field.

6. What happens when a current-carrying conductor is placed in a magnetic field?
Answer: The conductor experiences a force perpendicular to both the magnetic field and the current direction. If either the current or field direction is reversed, the force direction also reverses. The force is maximum when current and field are perpendicular.

7. Describe the construction and working of a domestic electric circuit.
Answer: Electricity enters a house through a main supply line with live and neutral wires. It passes through an electric meter and main fuse. Two circuits are used — one of 15A for heavy appliances and another of 5A for light appliances. All appliances are connected in parallel for equal voltage supply. Earth wire is used for safety.

8. What is the function of the earth wire? Why is earthing important?
Answer: The earth wire provides a low-resistance path to the ground for current leakage. It prevents electric shock by keeping the appliance body at earth potential. Hence, it protects users from electric hazards.

9. What are the causes and prevention of short-circuiting and overloading?
Answer:

Causes:

• Direct contact between live and neutral wires.
• Connecting too many appliances to one socket.

Prevention:

• Use proper wiring, avoid damaged insulation, and use fuses or circuit breakers to protect the circuit.

10. Differentiate between an electromagnet and a permanent magnet.
Answer: