1. The instrument used to measure current is called:
a) Voltmeter
b) Ammeter
c) Galvanometer
d) Wattmeter
Answer: b
Explanation: Ammeter measures electric current in a circuit.
2. The instrument used to measure potential difference is:
a) Voltmeter
b) Ammeter
c) Galvanometer
d) Ohmmeter
Answer: a
Explanation: Voltmeter is connected in parallel to measure voltage.
3. A galvanometer measures:
a) Current
b) Voltage
c) Resistance
d) Power
Answer: a
Explanation: Galvanometer measures small currents; can be converted to ammeter or voltmeter.
4. Conversion of galvanometer to ammeter is done by:
a) Series resistor
b) Parallel resistor
c) No resistor
d) Capacitor
Answer: b
Explanation: Low-resistance shunt is connected parallel to galvanometer.
5. Conversion of galvanometer to voltmeter is done by:
a) Series resistor
b) Parallel resistor
c) No resistor
d) Inductor
Answer: a
Explanation: High series resistance is added to galvanometer to measure voltage.
6. The tangent galvanometer measures:
a) Electric field
b) Magnetic field
c) Electric current
d) Resistance
Answer: c
Explanation: Measures current using the tangent law of magnetism.
7. Ballistic galvanometer is used to measure:
a) Steady current
b) Charge
c) Voltage
d) Resistance
Answer: b
Explanation: Measures total charge passed through in short time.
8. A potentiometer is used to measure:
a) Voltage
b) Current
c) Charge
d) Resistance
Answer: a
Explanation: Potentiometer measures emf or potential difference accurately without drawing current.
9. The Wheatstone bridge measures:
a) Current
b) Resistance
c) Voltage
d) Power
Answer: b
Explanation: Wheatstone bridge determines unknown resistance by balancing ratio of resistances.
10. Kelvin double bridge is used to measure:
a) Low resistance
b) High resistance
c) Voltage
d) Current
Answer: a
Explanation: Used for very low resistance measurements.
11. Carey-Foster bridge measures:
a) Very high resistance
b) Very low resistance
c) Medium resistance
d) Inductance
Answer: c
Explanation: Used for medium resistance measurement and comparison.
12. A thermocouple measures:
a) Electric current
b) EMF
c) Temperature
d) Magnetic field
Answer: c
Explanation: Generates EMF proportional to temperature difference between junctions.
13. Thermistor is:
a) A device whose resistance increases with temperature
b) A device whose resistance decreases with temperature
c) Measures EMF
d) Measures pressure
Answer: b
Explanation: Negative temperature coefficient; resistance decreases with temperature rise.
14. Strain gauge measures:
a) Pressure
b) Force
c) Strain
d) Voltage
Answer: c
Explanation: Resistance of strain gauge changes when stretched; used to measure strain.
15. Microammeter is used to measure:
a) Large currents
b) Small currents
c) Voltage
d) Power
Answer: b
Explanation: Measures microamperes (small currents).
16. Milliammeter measures:
a) Microamperes
b) Milliamperes
c) Amperes
d) Voltage
Answer: b
Explanation: Measures current in milliampere range.
17. The main part of a moving coil galvanometer is:
a) Coil suspended in magnetic field
b) Permanent magnet
c) Resistor
d) Capacitor
Answer: a
Explanation: Coil carrying current experiences torque in magnetic field.
18. D’Arsonval galvanometer operates on:
a) Moving coil principle
b) Moving iron principle
c) Electrostatic principle
d) Induction principle
Answer: a
Explanation: Uses torque on current-carrying coil in magnetic field.
19. Moving iron instrument measures:
a) Current only
b) AC and DC
c) Voltage only
d) Resistance
Answer: b
Explanation: Can measure both AC and DC because force depends on square of current.
20. PMMC instruments are:
a) Only for AC
b) Only for DC
c) For both AC and DC
d) None
Answer: b
Explanation: Permanent Magnet Moving Coil instruments work for DC only.
21. Rheostat is used to:
a) Measure voltage
b) Vary current
c) Measure resistance
d) Detect EMF
Answer: b
Explanation: Variable resistor used to control current in circuit.
22. Multimeter can measure:
a) Current, voltage, resistance
b) Current only
c) Voltage only
d) Resistance only
Answer: a
Explanation: Combines ammeter, voltmeter, ohmmeter in one instrument.
23. Ammeter should be connected:
a) In series
b) In parallel
c) Across load
d) Anywhere
Answer: a
Explanation: Series connection ensures all current passes through ammeter.
24. Voltmeter should be connected:
a) In series
b) In parallel
c) Across resistor only
d) In any way
Answer: b
Explanation: Parallel connection measures potential difference across component.
25. The accuracy of an instrument is defined as:
a) Ability to measure rapidly
b) Degree of closeness to true value
c) Ability to measure large values
d) Ability to measure small values
Answer: b
Explanation: Accuracy = closeness of measured value to true value.
26. A PMMC instrument can measure:
a) AC only
b) DC only
c) Both AC and DC
d) Resistance only
Answer: b
Explanation: Permanent Magnet Moving Coil instruments work only for DC.
27. Moving iron instruments can measure:
a) DC only
b) AC only
c) Both AC and DC
d) Voltage only
Answer: c
Explanation: Moving iron instruments respond to square of current, so they work for both AC and DC.
28. The main principle of voltmeter and ammeter is:
a) Electromagnetic induction
b) Deflection proportional to current
c) Electrostatic force
d) Magnetic flux
Answer: b
Explanation: Current passing through coil produces proportional deflection.
29. Shunt resistance in an ammeter is used to:
a) Increase current sensitivity
b) Reduce current sensitivity
c) Convert galvanometer to ammeter
d) Protect voltage
Answer: c
Explanation: Shunt allows most current to bypass galvanometer.
30. Series resistance in voltmeter is used to:
a) Increase sensitivity
b) Reduce sensitivity
c) Convert voltmeter to ammeter
d) Protect ammeter
Answer: a
Explanation: High series resistance limits current, allowing voltage measurement.
31. Earth leakage circuit breaker (ELCB) protects:
a) Voltage surges
b) Overcurrent
c) Leakage current to earth
d) Transformer
Answer: c
Explanation: Detects current leakage and disconnects supply.
32. A kilowatt-hour meter measures:
a) Power
b) Energy
c) Voltage
d) Current
Answer: b
Explanation: Measures energy consumption (kWh = power × time).
33. Energy meter works on:
a) Moving coil principle
b) Electromagnetic induction
c) Electrostatic principle
d) Magnetic saturation
Answer: b
Explanation: Uses induction principle: current and voltage coils produce torque proportional to power.
34. Ohmmeter measures:
a) Resistance directly
b) Current only
c) Voltage only
d) Power
Answer: a
Explanation: Measures resistance by passing known current through unknown resistor.
35. Megger is used to measure:
a) Low resistance
b) High resistance and insulation
c) Voltage
d) Current
Answer: b
Explanation: High voltage is applied to measure insulation resistance.
36. The unit of electrical resistance is:
a) Ohm
b) Farad
c) Henry
d) Volt
Answer: a
Explanation: 1 Ω = 1 V/A.
37. The Wheatstone bridge is used for:
a) Measuring voltage
b) Measuring resistance
c) Measuring current
d) Measuring power
Answer: b
Explanation: Determines unknown resistance by balancing a bridge circuit.
38. Kelvin double bridge is preferred for:
a) Medium resistance
b) High resistance
c) Very low resistance
d) Inductance
Answer: c
Explanation: Measures very low resistances accurately by minimizing contact resistance errors.
39. Maxwell’s bridge is used to measure:
a) Resistance
b) Inductance
c) Capacitance
d) Voltage
Answer: b
Explanation: Determines unknown inductance using a bridge with standard capacitance.
40. Schering bridge is used to measure:
a) Capacitance and dissipation factor
b) Inductance
c) Resistance
d) Voltage
Answer: a
Explanation: Measures capacitor parameters precisely.
41. Megger works on:
a) Moving coil
b) Electrostatic
c) Permanent magnet
d) Electromagnetic induction
Answer: d
Explanation: High-voltage DC generated by hand-cranked dynamo.
42. Ammeter should have:
a) High resistance
b) Low resistance
c) Medium resistance
d) Variable resistance
Answer: b
Explanation: Low resistance ensures minimal voltage drop in series.
43. Voltmeter should have:
a) High resistance
b) Low resistance
c) Medium resistance
d) Zero resistance
Answer: a
Explanation: High resistance prevents current draw from circuit.
44. AC energy meter can measure:
a) Instantaneous power
b) Average power
c) RMS power
d) Maximum power
Answer: c
Explanation: Measures average energy consumed over time using RMS values.
45. Rectifier type PMMC instruments can measure:
a) AC only
b) DC only
c) AC and DC
d) Resistance only
Answer: c
Explanation: AC is converted to DC by rectifier for PMMC deflection.
46. LCR meter measures:
a) Inductance, capacitance, resistance
b) Voltage only
c) Current only
d) Power only
Answer: a
Explanation: LCR meters provide precise measurement of L, C, and R.
47. The main purpose of a potentiometer is:
a) Measure current
b) Measure potential difference accurately
c) Measure resistance only
d) Measure power
Answer: b
Explanation: Measures EMF or potential difference without drawing current.
48. Capacitance can be measured by:
a) Wheatstone bridge
b) Schering bridge
c) Kelvin bridge
d) LCR meter
Answer: b
Explanation: Schering bridge or LCR meter used for precise capacitance measurement.
49. Galvanometer sensitivity is measured in:
a) Ohms
b) Volt/ampere
c) Deflection per unit current
d) Farad
Answer: c
Explanation: Sensitivity = deflection per unit current (e.g., mm/μA).
50. Digital multimeter works on:
a) Moving coil principle
b) Analog pointer
c) Analog-to-digital conversion
d) LCR principle
Answer: c
Explanation: Converts analog signals to digital display using ADC.
51. Spectrometer is used to measure:
a) Current
b) Wavelength of light
c) Resistance
d) Voltage
Answer: b
Explanation: Spectrometer accurately measures angles of light deviation to determine wavelength.
52. A telescope is used to:
a) Observe distant objects
b) Measure current
c) Measure voltage
d) Measure resistance
Answer: a
Explanation: Collects and magnifies light from distant objects.
53. A microscope increases:
a) Voltage
b) Current
c) Image magnification
d) Resistance
Answer: c
Explanation: Microscope magnifies small objects using lenses.
54. Plane mirror produces:
a) Real image
b) Virtual image
c) Both
d) No image
Answer: b
Explanation: Plane mirror produces upright virtual image behind mirror.
55. Concave mirror can produce:
a) Real image only
b) Virtual image only
c) Real or virtual image depending on object position
d) No image
Answer: c
Explanation: Object beyond focus → real, inverted; object inside focus → virtual, upright.
56. Convex lens produces:
a) Real image
b) Virtual image
c) Both
d) No image
Answer: c
Explanation: Object beyond focal length → real image; inside focal length → virtual image.
57. Focal length of lens is measured by:
a) Meter scale
b) Convex lens formula
c) Lens maker’s formula
d) Spectrometer
Answer: c
Explanation: 
58. Prism is used to:
a) Split light into spectrum
b) Measure current
c) Measure voltage
d) Measure resistance
Answer: a
Explanation: Dispersion separates light into constituent colors.
59. Refractive index of medium is:
a) Ratio of speed in medium to air
b) Ratio of speed in air to medium
c) Ratio of wavelength in medium to air
d) None
Answer: b
Explanation: 
, speed of light in vacuum or air divided by speed in medium.
60. Spectrophotometer is used to measure:
a) Wavelength of X-rays
b) Absorbance of light by solution
c) Current
d) Voltage
Answer: b
Explanation: Measures intensity of light transmitted through a sample.
61. Photometer measures:
a) Current
b) Brightness of light
c) Resistance
d) Capacitance
Answer: b
Explanation: Photometer measures luminous intensity or brightness.
62. Interference of light is observed using:
a) Telescope
b) Michelson interferometer
c) Spectrometer
d) Ammeter
Answer: b
Explanation: Michelson interferometer produces fringe patterns for wavelength measurement.
63. Diffraction of light is studied using:
a) Grating
b) Single slit
c) Polarizer
d) Lens
Answer: b
Explanation: Single slit diffraction causes spreading and fringes.
64. Polarizer is used to:
a) Split light
b) Convert unpolarized light to polarized light
c) Measure intensity
d) Measure wavelength
Answer: b
Explanation: Polarizer allows only electric field along certain direction to pass.
65. Optical fiber works on:
a) Diffraction
b) Total internal reflection
c) Polarization
d) Refraction
Answer: b
Explanation: Light is guided inside core by total internal reflection.
66. X-ray tube works on:
a) Electron acceleration and deceleration
b) Electron capture
c) Alpha decay
d) Gamma emission
Answer: a
Explanation: High-speed electrons strike target; sudden deceleration produces X-rays.
67. Geiger-Müller counter detects:
a) Voltage
b) Current
c) Ionizing radiation
d) Resistance
Answer: c
Explanation: Detects α, β, γ radiation using ionization in gas.
68. Scintillation counter uses:
a) Fluorescent screen
b) Ionization
c) Magnetic field
d) Thermistor
Answer: a
Explanation: Detects radiation via light flashes in scintillator crystal.
69. Photomultiplier tube amplifies:
a) Light signal
b) Current
c) Voltage
d) Resistance
Answer: a
Explanation: Converts weak light signals into amplified electric signals.
70. X-ray diffraction is used to study:
a) Resistance
b) Crystal structure
c) Voltage
d) Current
Answer: b
Explanation: X-rays interact with crystal lattice, giving diffraction patterns.
71. Bragg’s law is:
a) 
b) 
c) 
d) 
Answer: a
Explanation: Describes constructive interference of X-rays in crystal planes.
72. Cloud chamber is used to observe:
a) Electric current
b) Path of ionizing particles
c) Light intensity
d) Voltage
Answer: b
Explanation: Tracks left by α, β particles in supersaturated vapor.
73. Wilson cloud chamber uses:
a) Supersaturated vapor
b) Condensed water only
c) Gas discharge
d) Laser
Answer: a
Explanation: Vapor condenses along ionized paths of radiation.
74. Bubble chamber is filled with:
a) Water
b) Superheated liquid
c) Gas
d) Metal
Answer: b
Explanation: Charged particles leave trails of bubbles in superheated liquid.
75. Geiger-Müller counter cannot measure:
a) Alpha
b) Beta
c) Gamma
d) Neutrinos
Answer: d
Explanation: Neutrinos interact very weakly; undetectable by GM counter.
76. Digital multimeter works on:
a) Moving coil principle
b) Moving iron principle
c) Analog-to-digital conversion
d) Electrostatic principle
Answer: c
Explanation: Converts analog signals to digital display using ADC circuits.
77. CRO (Cathode Ray Oscilloscope) measures:
a) Voltage vs time
b) Current vs resistance
c) Power vs voltage
d) Energy
Answer: a
Explanation: CRO displays variation of voltage over time on screen.
78. CRO works on:
a) Cathode ray tube
b) Moving coil
c) Moving iron
d) Electrostatic principle
Answer: a
Explanation: Uses electron beam deflection in CRT to display signals.
79. Storage oscilloscope is used to:
a) Measure DC only
b) Capture and store transient signals
c) Measure resistance
d) Measure current
Answer: b
Explanation: Can hold and display rapidly varying or transient signals.
80. Lissajous figures on CRO are used to determine:
a) Resistance
b) Frequency ratio and phase difference
c) Voltage only
d) Current only
Answer: b
Explanation: Patterns formed on CRO by two perpendicular signals reveal frequency and phase relation.
81. Digital frequency meter measures:
a) Voltage
b) Frequency
c) Resistance
d) Current
Answer: b
Explanation: Counts number of cycles per second of periodic signal.
82. Phase sequence indicator is used in:
a) DC circuits
b) Three-phase AC systems
c) Single-phase AC circuits
d) Transformers only
Answer: b
Explanation: Determines correct phase rotation in three-phase systems.
83. Digital storage oscilloscope (DSO) converts:
a) Voltage to current
b) Analog waveform to digital waveform
c) AC to DC
d) None
Answer: b
Explanation: Captures, digitizes, and stores signal for display and analysis.
84. Hall effect sensor measures:
a) Current only
b) Magnetic field
c) Voltage only
d) Resistance
Answer: b
Explanation: Produces voltage perpendicular to current in magnetic field.
85. Digital thermometer works on:
a) Thermocouple and ADC
b) Mercury
c) Alcohol expansion
d) Resistance only
Answer: a
Explanation: Thermocouple produces EMF converted to temperature digitally.
86. Gauss meter measures:
a) Electric field
b) Magnetic field
c) Voltage
d) Current
Answer: b
Explanation: Measures magnetic flux density (in Gauss or Tesla).
87. Photoelectric cell converts:
a) Light energy to heat
b) Light energy to electrical energy
c) Electrical energy to light
d) Sound to electrical energy
Answer: b
Explanation: Emits electrons when exposed to light (photoelectric effect).
88. Laser is used in:
a) Communication
b) Surgery
c) Cutting metals
d) All of the above
Answer: d
Explanation: Coherent light with high intensity has multiple applications.
89. Fiber optic sensor detects:
a) Light only
b) Temperature, pressure, displacement via light modulation
c) Current
d) Voltage
Answer: b
Explanation: Light intensity or phase changes are used to sense physical quantities.
90. CCD (Charge Coupled Device) is used in:
a) Digital cameras and imaging
b) Resistance measurement
c) Thermometry
d) Voltmeter
Answer: a
Explanation: Converts optical image into electronic signal in cameras or telescopes.
91. Interferometer is used to measure:
a) Distance, wavelength, refractive index
b) Current
c) Voltage
d) Resistance
Answer: a
Explanation: Uses interference of light to measure precise physical quantities.
92. Michelson interferometer was used to measure:
a) Speed of light
b) Wavelength of light
c) Electric current
d) Voltage
Answer: a
Explanation: Michelson-Morley experiment used it to detect ether; can measure wavelength and light speed.
93. Ultrasonic detector uses:
a) Sound waves >20 kHz
b) Light waves
c) Electric waves
d) Magnetic waves
Answer: a
Explanation: Detects high-frequency sound waves above human hearing.
94. Thermocouple pyrometer measures:
a) Low temperature
b) High temperature
c) Current
d) Voltage
Answer: b
Explanation: Measures high temperatures using EMF produced by thermocouple.
95. Pyrometer measures:
a) Electric current
b) Temperature of hot bodies without contact
c) Resistance
d) Voltage
Answer: b
Explanation: Non-contact measurement via radiation emitted from hot object.
96. Atomic absorption spectrometer measures:
a) Concentration of elements in sample
b) Voltage
c) Current
d) Resistance
Answer: a
Explanation: Measures light absorbed by atoms vaporized in flame or furnace.
97. Mass spectrometer is used to measure:
a) Mass-to-charge ratio of ions
b) Voltage
c) Current
d) Resistance
Answer: a
Explanation: Separates ions based on mass/charge ratio using magnetic/electric fields.
98. Geiger-Müller counter detects:
a) Neutrinos
b) Ionizing radiation
c) Magnetic field
d) Electric field
Answer: b
Explanation: Detects α, β, γ radiation by ionization in gas-filled tube.
99. Scintillation detector uses:
a) Light emission in crystal
b) Thermal effect
c) Magnetic deflection
d) Resistance variation
Answer: a
Explanation: Radiation produces light pulses in scintillator; converted to electrical signal.
100. Modern scientific instruments often combine:
a) Analog measurement only
b) Digital display, data acquisition, and automation
c) Mechanical measurement only
d) None
Answer: b
Explanation: Advanced instruments integrate sensors, ADCs, display, and computer interface for precision and convenience.