Physics MCQs – Set 15: High-Level Questions for UPSC/PCS Exam Prep

  1. Radioactivity was discovered by –
    (A) Einstein
    (B) Roentgen
    (C) Rutherford
    (D) Henri Becquerel
    Answer: (D)
  2. A moving coil galvanometer can be converted into a voltmeter by connecting –
    (A) Low resistance in parallel
    (B) High resistance in series
    (C) High resistance in parallel
    (D) Low resistance in series
    Answer: (B)
  3. The unit of electric potential is –
    (A) Ampere
    (B) Coulomb
    (C) Ohm
    (D) Volt
    Answer: (D)
  4. A laser produces –
    (A) Incoherent light
    (B) Monochromatic and coherent light
    (C) White light
    (D) Infrared light only
    Answer: (B)
  5. A liquid drop assumes spherical shape due to –
    (A) Viscosity
    (B) Surface tension
    (C) Gravity
    (D) Adhesion
    Answer: (B)
  6. The velocity-time graph of a uniformly accelerated body is –
    (A) Straight line
    (B) Curve
    (C) Parabola
    (D) Hyperbola
    Answer: (A)
  7. The focal length of a convex mirror is –
    (A) Positive
    (B) Negative
    (C) Zero
    (D) Variable
    Answer: (B)
  8. Beta rays are –
    (A) Protons
    (B) Electrons
    (C) Neutrons
    (D) Alpha particles
    Answer: (B)
  9. A cyclotron is a device used to –
    (A) Split atoms
    (B) Accelerate charged particles
    (C) Produce electricity
    (D) Amplify signals
    Answer: (B)
  10. Spectacles for hypermetropia use –
    (A) Concave lenses
    (B) Convex lenses
    (C) Plane mirrors
    (D) Cylindrical lenses
    Answer: (B)
  11. Gravitational potential energy is –
    (A) Always positive
    (B) Always negative
    (C) Zero
    (D) Positive or negative
    Answer: (B)
  12. The dimension of velocity is –
    (A) LT⁻²
    (B) LT⁻¹
    (C) L²T
    (D) L²T⁻²
    Answer: (B)
  13. A light ray enters a denser medium and –
    (A) Speeds up
    (B) Slows down
    (C) Refracts away
    (D) Travels straight
    Answer: (B)
  14. Solar cells work on –
    (A) Thermoelectric effect
    (B) Photoelectric effect
    (C) Seebeck effect
    (D) Electromagnetic induction
    Answer: (B)
  15. The capacity of a capacitor is determined by –
    (A) Shape of plates
    (B) Area and separation of plates
    (C) Plate material
    (D) External circuit
    Answer: (B)
  16. Centripetal force acts –
    (A) Outward
    (B) Inward
    (C) Tangentially
    (D) Vertically
    Answer: (B)
  17. A bar magnet suspended freely aligns –
    (A) North–South
    (B) East–West
    (C) Randomly
    (D) Vertically
    Answer: (A)
  18. Latent heat is –
    (A) Heat to change temperature
    (B) Heat to change state
    (C) Heat to raise volume
    (D) None of these
    Answer: (B)
  19. A motor converts –
    (A) Electrical to mechanical energy
    (B) Mechanical to electrical energy
    (C) Thermal to mechanical
    (D) Electrical to thermal
    Answer: (A)
  20. The total resistance in a series circuit is –
    (A) Zero
    (B) Average of resistors
    (C) Equal to sum of individual resistances
    (D) Product of all resistances
    Answer: (C)
  21. The optical density of a medium depends on –
    (A) Mass
    (B) Refractive index
    (C) Color
    (D) Transparency
    Answer: (B)
  22. Plasma state of matter is –
    (A) Solid
    (B) Ionized gas
    (C) Superfluid
    (D) Bose-Einstein condensate
    Answer: (B)
  23. The main component of natural gas is –
    (A) Butane
    (B) Methane
    (C) Ethane
    (D) Propane
    Answer: (B)
  24. Pascal’s law is applied in –
    (A) Barometer
    (B) Hydraulic press
    (C) Manometer
    (D) Thermometer
    Answer: (B)
  25. A graph of acceleration vs. time for uniformly accelerating object is –
    (A) Straight line parallel to time axis
    (B) Parabola
    (C) Curve
    (D) Zero
    Answer: (A)
  26. The power of a lens is measured in –
    (A) Diopters
    (B) Watts
    (C) Lux
    (D) Lumen
    Answer: (A)
  27. The rate of change of momentum is –
    (A) Energy
    (B) Force
    (C) Pressure
    (D) Work
    Answer: (B)
  28. SI unit of luminous intensity is –
    (A) Lumen
    (B) Lux
    (C) Candela
    (D) Diopter
    Answer: (C)
  29. A body moving in circle with uniform speed has –
    (A) Constant velocity
    (B) Constant acceleration
    (C) Constant momentum
    (D) Changing velocity
    Answer: (D)
  30. Light is fastest in
    (A) Diamond
    (B) Water
    (C) Air
    (D) Vacuum
    Answer: (D)
  31. A good conductor has –
    (A) Low resistivity
    (B) High resistance
    (C) High specific heat
    (D) High expansion
    Answer: (A)
  32. The law of conservation of momentum is derived from –
    (A) Newton’s 1st law
    (B) Newton’s 2nd law
    (C) Newton’s 3rd law
    (D) Work–Energy Theorem
    Answer: (C)
  33. A gas thermometer is more accurate because –
    (A) Gases expand linearly
    (B) Gases respond quickly
    (C) Gases don’t freeze
    (D) Gases follow ideal behavior
    Answer: (D)
  34. The cooling in a refrigerator is due to –
    (A) Loss of heat by compressor
    (B) Evaporation of liquid
    (C) Expansion of gas
    (D) Compression of refrigerant
    Answer: (B)
  35. Mirage is observed due to –
    (A) Reflection
    (B) Total internal reflection
    (C) Refraction
    (D) Absorption
    Answer: (B)
  36. The instrument to detect electric current is –
    (A) Voltmeter
    (B) Galvanometer
    (C) Potentiometer
    (D) Barometer
    Answer: (B)
  37. A simple harmonic motion is –
    (A) Periodic and non-uniform
    (B) Non-periodic
    (C) Uniform and linear
    (D) Periodic and has restoring force
    Answer: (D)
  38. The electrical conductivity of a semiconductor –
    (A) Increases with temperature
    (B) Decreases with temperature
    (C) Is constant
    (D) Is zero
    Answer: (A)
  39. A compressed spring has –
    (A) Kinetic energy
    (B) Potential energy
    (C) Thermal energy
    (D) Electric energy
    Answer: (B)
  40. A decibel is a unit of –
    (A) Frequency
    (B) Sound intensity
    (C) Pitch
    (D) Tone
    Answer: (B)
  41. SI unit of angular frequency is –
    (A) rad/s
    (B) Hz
    (C) rpm
    (D) cycles/s
    Answer: (A)
  42. A force acting on a body for short time is called –
    (A) Pressure
    (B) Impact
    (C) Impulse
    (D) Tension
    Answer: (C)
  43. The best conductor of heat is –
    (A) Iron
    (B) Copper
    (C) Aluminum
    (D) Silver
    Answer: (D)
  44. The minimum energy needed to eject an electron is –
    (A) Threshold frequency
    (B) Potential
    (C) Work function
    (D) Voltage
    Answer: (C)
  45. A liquid boils when
    (A) Surface vaporizes
    (B) Temperature falls
    (C) Vapor pressure equals atmospheric pressure
    (D) Heat is absorbed
    Answer: (C)
  46. SI unit of thermal conductivity is –
    (A) W/m·K
    (B) J/kg·K
    (C) Cal/m·s·K
    (D) W/cm·K
    Answer: (A)
  47. SI unit of frequency is –
    (A) Hertz
    (B) Radian
    (C) Second
    (D) Newton
    Answer: (A)
  48. A good reflector of sound is –
    (A) Cloth
    (B) Water
    (C) Concrete wall
    (D) Curtain
    Answer: (C)
  49. A ball dropped from height has –
    (A) Constant velocity
    (B) Constant momentum
    (C) Increasing speed
    (D) Zero force
    Answer: (C)
  50. A dyne is the CGS unit of –
    (A) Pressure
    (B) Force
    (C) Energy
    (D) Momentum
    Answer: (B)

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