Free Electromagnetism MCQs with Answers

• A. Electron
• B. X-plates
• C. Protons
• D. Y-plates

Explanation: In a cathode ray oscilloscope (CRO), the hot metal filament emits electrons through a process called thermionic emission.

• A. By heating a metal filament
• B. By ionisation of the air
• C. By applying an electric field
• D. None of these

Explanation: Electrons are produced in a cathode ray oscilloscope (CRO) by heating a metal filament through a process called thermionic emission.

• A. To control the number of electrons accelerated by anode
• B. To control trilaterals of spot formed on the screen
• C. Both (a) and (b)
• D. None of these

Explanation: While the grid does control the intensity of the electron beam and influences the number of electrons reaching the screen, its primary…

• A. Grid
• B. Three anodes
• C. Indirectly heated cathode
• D. All of the above

Explanation: The electron gun in a cathode ray oscilloscope includes an indirectly heated cathode.

• A. Angle of deflection
• B. Magnetic field
• C. Number of turns
• D. Resistance of the coil

Explanation: In a galvanometer, the current passing through the coil is not directly proportional to the angle of deflection.

• A. Mass
• B. α-particle
• C. β-particle
• D. Proton

Explanation: When a charged particle moves through a magnetic field, it experiences a force called the magnetic Lorentz force, which acts perpendicular…

• A. Material of the coil
• B. Torque exerted on the coil
• C. Magnetic force exerted on the coil
• D. None of the above

Explanation: The working of a galvanometer does depend on the factors mentioned above, particularly the material of the coil and the torque exerted on…

• A. Very small
• B. Very high
• C. Neither small nor high
• D. None of the above

Explanation: For accurate measurement of current through a circuit, the resistance of the ammeter should ideally be very small.

• A. Parallel
• B. Series
• C. Some times in series and some times in parallel
• D. None of the above

Explanation: When measuring potential difference (voltage) across a component like a resistor, the voltmeter is connected in parallel with the…

• A. Ammeter
• B. Voltmeter
• C. AVO meter
• D. Ohm meter

Explanation: AVO meter is a combined instrument that can measure current (amperes), potential difference (volts), and resistance (ohms).

• A. Rough
• B. Fluorescent
• C. Polished
• D. Clear

Explanation: The screen of a CRO is coated with a fluorescent material that emits light when struck by electrons.

• A. Protons
• B. Electrons
• C. Rays
• D. Radiation

Explanation: When the cathode of a CRO is heated by a filament, a process known as thermionic emission occurs.

• A. Tesla
• B. Gauss
• C. Newton
• D. Ampere

Explanation: Newton is the SI unit of force. It represents the amount of force required to accelerate a one-kilogram mass by one meter per second…

• A. Coil placed in a magnetic field
• B. Coil placed in an electric field
• C. Coil and a scale only
• D. None of these

Explanation: A galvanometer typically consists of a coil of wire (often called the moving coil) that is suspended in a magnetic field provided by…

• A. Concave shaped
• B. Convex shaped
• C. Plane-shaped
• D. Spherical shaped

Explanation: Concave refers to a surface or structure that curves inward, like the inner surface of a bowl.

• A. Enamelled steel wire
• B. Copper wire
• C. Enamelled copper wire
• D. None of these

Explanation: Enamelled copper wire is a type of copper wire that is coated with a thin layer of insulation, typically made of enamel.

• A. Soft iron cylinder
• B. Soft steel cylinder
• C. Soft copper cylinder
• D. None of these

Explanation: Soft iron is a ferromagnetic material that can easily become magnetised in the presence of an external magnetic field.

• A. Chemical effect
• B. Magnetic effect
• C. Heating effect
• D. All

Explanation: The magnetic effect of current, also known as the Ampere's law, is the phenomenon where an electric current flowing through a conductor…

• A. Magnetic material
• B. An insulator
• C. A conductor
• D. Non-magnetic material

Explanation: While the core material for the coil in a galvanometer is typically chosen to be non-magnetic to prevent interference with the magnetic…

• A. Exponential
• B. Circular
• C. Linear
• D. None

Explanation: While the output scale of a galvanometer can be linear, especially for applications where a direct reading of current magnitude is…