Class 10 Science Chapter 12 Practice Question Answers - Magnetic Effects of Electric Current

Fill in the Blanks
Q1: The property of a substance to attract or repel another substance is known as ___________.
Ans: Magnetism.

Q2: The current-carrying conductor is surrounded by a magnetic field, which is in the form of ___________ lines.
Ans: Magnetic field lines.

Q3: The SI unit of magnetic field strength is ___________.
Ans: Tesla (T).

Q4: The magnetic field inside a current-carrying solenoid is ___________ and uniform.
Ans: Strong.

Q5: The device used to detect the presence of current in a circuit is called a ___________.
Ans: Galvanometer.

Short Answer Questions
Q6: How does the strength of the magnetic field produced by a current-carrying conductor change when the current is increased?
Ans: The strength of the magnetic field increases with an increase in current.

Q7: Explain why the North pole of a magnet gets attracted to the South pole of another magnet.
Ans: This attraction occurs due to the alignment of magnetic domains in opposite directions, creating a stronger combined magnetic field.

Q8: State Ampere's law.
Ans: Ampere's law states that the magnetic field around a closed loop is directly proportional to the electric current passing through the loop.

Q9: What is the purpose of using a soft iron core in an electromagnet?
Ans: A soft iron core enhances the magnetic field strength in an electromagnet by providing a path for the magnetic lines of force to concentrate.

Q10: Describe the rule to determine the direction of the magnetic field using the right-hand thumb rule.
Ans: Point your thumb in the direction of the current flow, and your curled fingers indicate the direction of the magnetic field around the conductor.

Long  Answer Questions
Q11: Explain the working principle of an electric motor.
Ans: An electric motor operates on the principle of electromagnetic induction. When current flows through a coil (armature) placed in a magnetic field, a force is exerted on the coil due to the interaction between the magnetic field and the current. This force causes the coil to rotate, resulting in mechanical motion.

Q12: Compare the working of a direct current (DC) motor and an alternating current (AC) motor.
Ans: A DC motor operates on direct current and uses a split-ring commutator to reverse the direction of current in the coil, causing continuous rotation. An AC motor operates on alternating current and doesn't require a commutator. The direction of current in the coil changes with each half-cycle, causing the rotor to turn.

Q13: How does an electric bell work?
Ans: An electric bell consists of an electromagnet, a hammer, and a gong. When the current flows through the coil, it generates a magnetic field that attracts the iron armature, causing the hammer to strike the gong. This interrupts the circuit, and the magnetic field collapses. The armature returns to its original position due to a spring, completing the circuit again. This cycle repeats, producing the bell's ringing sound.

Q14: State and explain Fleming's left-hand rule for the direction of the force experienced by a current-carrying conductor placed in a magnetic field.
Ans: According to Fleming's left-hand rule, if the forefinger, thumb, and middle finger of the left hand are held perpendicular to each other, with the forefinger representing the magnetic field direction (B), the middle finger representing the current direction (I), then the thumb indicates the direction of the force (F) experienced by the conductor.

Q15: Describe the construction and working of a simple DC generator.
Ans: A simple DC generator consists of a rectangular coil of wire rotating between the poles of a permanent magnet. When the coil rotates, it cuts across the magnetic field lines, inducing an electromotive force (EMF) or voltage in the coil. This EMF causes current to flow through the external circuit when the coil is connected to a load. The split-ring commutator reverses the direction of current in the coil at each half-rotation, resulting in a unidirectional current output.