🧲 Chapter 17: Electromagnetism – Exercise Short Questions
Prepared by Muhammad Tayyab, Subject Specialist Physics, Govt Christian High School Daska. Based on PECTAA 2026 syllabus (National Curriculum 2023).
📖 What's Inside: This section covers exercise short questions from Chapter 17 Electromagnetism including direction of magnetic field around a straight wire, effect of current on magnetic field strength, identifying poles of a magnet, Fleming's left-hand rule, role of commutator in D.C motor, and the source of Earth's magnetic field. Each question is presented with a precise answer as per the official PECTAA 2026 Physics curriculum. Perfect for Punjab Boards (Lahore, Gujranwala, Multan, etc.) and all BISE boards across Pakistan.
📚 Related Resources – Chapter 17: Electromagnetism
Electromagnetism covers magnetic fields, right-hand grip rule, force on conductors, D.C motor, relay, loudspeaker, and Earth's magnetic field.
📝 Exercise Short Questions & Answers (PECTAA 2026)
17.1 What is the direction of the magnetic field around a straight current carrying wire?
Answer: The direction of the magnetic field around a straight current-carrying wire can be found using the right-hand grip rule.
According to the Right-Hand Grip Rule: If you hold the wire in your right hand with your thumb pointing in the direction of the current, then your fingers curl around the wire in the direction of the magnetic field.
✅ Thumb = Current direction, Fingers = Magnetic field direction.
17.2 What happens to the magnetic field if the magnitude of the current in a wire is increased?
Answer: If the magnitude of the current in a wire is increased, the magnetic field becomes stronger. The magnetic strength can be controlled by adjusting the current.
✅ Increasing current strengthens the magnetic field.
17.3 How can you identify the north and south poles of an unmarked magnetized steel bar?
Answer: Suspend the magnetized steel bar freely by a thread so that it can rotate. When it comes to rest, the end pointing towards the geographical north is the north pole, and the opposite end is the south pole.
✅ End pointing to geographical north is the north pole.
17.4 What rule determines the direction of force on a current-carrying conductor placed in a magnetic field? Explain briefly.
Answer: Fleming's left-hand rule determines the direction of force on a current-carrying conductor placed in a magnetic field.
Explanation:
Extend the thumb, forefinger, and middle finger of the left hand so that they are at right angles to one another. If the forefinger represents the magnetic field direction and the middle finger shows the current direction, then the thumb will point in the direction of the force acting on the conductor.
✅ Forefinger = Field, Middle finger = Current, Thumb = Force.
17.5 What role does the commutator play in a D.C. motor?
Answer: The split-ring commutator reverses the direction of current in the coil just as it reaches the vertical position. As a result, the direction of the forces on the coil is also reversed, allowing the coil to continue rotating continuously.
✅ Commutator reverses current direction to ensure continuous rotation.
17.6 What is the source of the Earth's magnetic field according to the theory?
Answer: According to the theory, Earth's magnetic field is generated by the movement of liquid metal in its core, a process known as the dynamo effect. As the Earth spins, the molten iron and nickel in the outer core create electric currents that produce the Earth's magnetic field.
✅ Dynamo effect: Movement of liquid metal in Earth's core generates the magnetic field.
🧲 Key Concepts – Electromagnetism
Right-Hand Grip Rule (Straight Wire): Thumb = Current, Fingers = Magnetic field.
Fleming's Left-Hand Rule: Forefinger = Field, Middle finger = Current, Thumb = Force.
Dynamo Effect: Movement of liquid metal in Earth's core generates electric currents and magnetic field.
Unit 10Thermal Physics
Unit 11Transfer of Thermal Energy
Unit 12Waves
Unit 13Sound
Unit 14Light
Unit 15Electrostatics
Unit 16Electricity
Unit 17✨ Electromagnetism
Unit 18Electromagnetic Induction & EM Waves
Unit 19Electronics
Unit 20Atomic and Nuclear Physics
Unit 21Space and Environment
📖 Complete syllabus coverage for Class 10 Physics (PECTAA 2026) – Units 10 to 21
💡 Exam Tip:
For exercise short questions, write precise and to-the-point answers. Use key terms like "right-hand grip rule", "Fleming's left-hand rule", "commutator", and "dynamo effect" as they are commonly tested in exams. These questions follow the PECTAA 2026 pattern and are prepared by Subject Specialist Muhammad Tayyab.
Created by Hira Science Academy | Aligned with PECTAA 2026 Syllabus