Free Electromagnetism MCQs with Answers

• A. Faraday's law
• B. Ampere's law
• C. Flemming's law
• D. Gauss's law

Explanation: Ampere's law relates the magnetic field around a closed loop to the electric current passing through the loop.

• A. Ammeter
• B. Galvanometer
• C. Voltmeter
• D. All of the above

Explanation: A galvanometer is a sensitive instrument used to detect and measure small electric currents.

• A. Area of the coil
• B. Strength of magnetic field
• C. Number of turns of the coil
• D. All of these

Explanation: All of these: Therefore, all of the options (increasing the area of the coil, the strength of the magnetic field, and the number of turns…

• A. Positrons
• B. Electrons
• C. Protons
• D. Both electrons and protons

Explanation: Electrons are negatively charged subatomic particles that are emitted from the cathode (negative electrode) of the cathode ray tube (CRT)…

• A. In milli amperes
• B. In nano amperes
• C. In amperes
• D. In divisions of angle of twist

Explanation: Galvanometers operate based on the principle of electromagnetic induction, where the current passing through a coil generates a magnetic…

• A. A low resistance in series
• B. A low resistance in parallel
• C. A high resistance in series
• D. None of these

Explanation: This option is correct. To convert a moving coil galvanometer into an ammeter, a low resistance, known as a shunt resistor, is connected…

• A. High resistance in series
• B. Low resistance in parallel
• C. High resistance in parallel
• D. None of these

Explanation: To convert a galvanometer into a voltmeter, a high resistance, known as a multiplier resistor, is connected in series with the…

• A. A.C generator
• B. Cathode ray oscilloscope
• C. D.C generator
• D. Galvanometer

Explanation: A cathode ray oscilloscope is a device used to display and analyse the waveform of electrical signals.

• A. Deflecting torque
• B. Ordinary torque
• C. Reflecting torque
• D. None of these

Explanation: In a galvanometer, the coil is suspended within a magnetic field and carries the current to be measured.

• A. Uniform magnetic field
• B. Uniform electric field between two sets of parallel plates
• C. Non-uniform magnetic field
• D. None of these

Explanation: This is the correct option. A CRO works by deflecting a beam of electrons as they pass through a non-uniform magnetic field.

• A. Filament heats the cathode
• B. Cathode heats the filament
• C. Grid heats the filament
• D. None of these

Explanation: In an indirectly heated cathode, the filament (also known as the heater) is responsible for heating the cathode.

• A. Lower potential w.r.t cathode
• B. Higher potential w.r.t to cathode
• C. Same potential as cathode
• D. None of these

Explanation: In a Cathode Ray Oscilloscope (CRO), the anode (also known as the accelerating anode) is typically maintained at a higher potential…

• A. Negative potential w.r.t to anode
• B. Positive potential w.r.t to anode
• C. Negative potential w.r.t to cathode
• D. Both (a) and (b)

Explanation: The grids in a CRO are typically at a negative potential with respect to the cathode.

• A. Power deflecting plates
• B. Two sets of deflecting plates
• C. Three sets of deflecting plates
• D. None of these

Explanation: In a CRO, there are typically two sets of deflecting plates, one for horizontal deflection and the other for vertical deflection.

• A. Vertically on the screen
• B. Horizontally on the screen
• C. Both (a) and (b)
• D. None of these

Explanation: The voltage applied across the Y-plate (vertical deflecting plates) deflects the electron beam vertically on the screen of the Cathode Ray…

• A. Vertically or the screen
• B. Horizontally on the screen
• C. Both (a) and (b)
• D. None of these

Explanation: The voltage applied across the X-plate (horizontal deflecting plates) deflects the electron beam horizontally on the screen of the Cathode…

• A. Circular
• B. Square
• C. Sinusoidal
• D. Saw-toothed

Explanation: The output waveform of the time base generator in a CRO is typically a saw-tooth waveform.

• A. Decreases linearly with time
• B. Increases linearly with time
• C. Increases linearly with time and then drops to zero
• D. None of these

Explanation: In a saw-tooth waveform, the voltage increases linearly with time, but instead of dropping to zero, it rapidly drops back to its starting…

• A. Frequency of voltage
• B. Voltage
• C. Phase of voltage
• D. All of above

Explanation: A CRO is indeed capable of measuring frequency and displaying voltage waveforms, so this option is not accurate.

• A. A voltmeter
• B. Wave shape of rapidly charging lubricants
• C. Measuring time interval between electrical plates
• D. All of the above

Explanation: Given the versatility and functionality of a CRO, it can indeed be used for all the purposes mentioned above.