Physics MCQs
Topic Notes: Physics
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
1
How does the intensity of the magnetic field change as one moves closer to a current-carrying conductor?
Answer:
stronger
According to Ampere's Law and the Biot-Savart Law, the magnetic field strength around a straight current-carrying wire is inversely proportional to the distance from the conductor. Therefore, as the distance decreases, the magnetic field intensity increases, becoming stronger.
2
Evaluate the relationship between the following statements: Statement I: A compass needle deflects near a current-carrying wire. Statement II: A current-carrying wire generates a magnetic field.
Answer:
Statement I and statement II are correct and statement II is the correct explanation of statement I
Oersted's experiment demonstrated that an electric current flowing through a conductor creates a magnetic field in the surrounding space. A compass needle, being a small magnet, experiences a torque in this magnetic field, causing it to deflect. Thus, Statement II provides the physical mechanism that explains the observation described in Statement I.
3
Which scientist is credited with discovering that an electric current flowing through a conductor generates a surrounding magnetic field?
Answer:
Ampere
The discovery that electric currents produce magnetic fields is fundamentally associated with Hans Christian Oersted, but André-Marie Ampère formulated the mathematical laws describing this relationship. Ampère's work established the foundation for electrodynamics, showing that the magnetic field around a conductor is directly proportional to the current flowing through it.
4
The orientation of a magnetic field generated by a conductor is determined by the direction of which physical quantity?
Answer:
current
According to Ampere's Law and the right-hand grip rule, the direction of the magnetic field lines around a current-carrying conductor is directly determined by the direction of the electric current flowing through that conductor.
5
According to the right-hand grip rule, if you grasp a current-carrying wire with your right hand such that your thumb points in the direction of the conventional current, what do your curling fingers indicate?
Answer:
magnetic field
The right-hand grip rule is a mnemonic used to determine the direction of the magnetic field lines around a current-carrying conductor. When the thumb points in the direction of the current, the fingers curl in the direction of the magnetic field lines, which form concentric circles around the wire.
6
What is the dimensional formula for magnetic field intensity (H)?
Answer:
IL-1
Magnetic field intensity (H) is related to the current (I) and length (L) by Ampere's Law, where H is proportional to I/L. Therefore, the dimensions are current divided by length, expressed as [I][L^-1].
7
How do two parallel wires carrying electric currents in opposite directions interact with each other?
Answer:
repel each other
According to Ampere's force law, parallel wires carrying current in the same direction attract each other, while wires carrying current in opposite directions exert a repulsive force on one another. This is due to the interaction between the magnetic field produced by one wire and the current flowing through the other.
8
Who discovered that the force exerted on a current-carrying wire in a magnetic field is perpendicular to both the field direction and the current direction?
Answer:
Ampere
André-Marie Ampère conducted foundational experiments in electromagnetism. He formulated the law describing the force between current-carrying conductors and established the relationship between the direction of the current, the magnetic field, and the resulting force, which is perpendicular to both.
9
Which rule is commonly used to determine the direction of the magnetic field lines generated around a current-carrying conductor?
Answer:
right hand grip rule
The right-hand grip rule is a mnemonic used to determine the direction of the magnetic field around a wire. If you point your right thumb in the direction of the conventional current, your curled fingers indicate the direction of the magnetic field lines circling the conductor.
10
What physical phenomenon is generated in the space surrounding a conductor carrying an electric current?
Answer:
An electro-magnetic field
A current-carrying conductor generates both an electric field (due to the potential difference) and a magnetic field (due to the flow of charge). Together, these constitute an electromagnetic field. While the magnetic component is often the focus in circuit analysis, the presence of moving charges inherently links both fields as described by Maxwell's equations.