Important Top 50 MCQs of Physics for Competitive Exams

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List of Important MCQs Of Physics For Competitive Exams

1. Consider the following:

Convex lens
Concave lens
Concave mirror
Convex mirror
Plane mirror

Which of the above can form a real image of a real object?
(A) Only 1 & 2
(B) Only 1 & 3
(C) Only 2, 3 & 4
(D) Only 1, 3, 4 & 5

Answer: (B) Only 1 & 3

2. Which of the following is correct about Pressure?
(A) Pressure is a scalar quantity
(B) Pressure is a vector quantity
(C) Pressure is a scalar quantity but obeys vector laws
(D) None of the above

Answer: (A) Pressure is a scalar quantity

3. Which of the following is the largest unit of energy
(a) Electron volt
(b) Joule
(c) Calorie
(d) Erg

Answer: (c) Calorie

4. Select the factor that affects the heat of reaction which is based on Kirchoff’s equation
(a) Molecularity
(b) Temperature
(c) Pressure
(d) Volume

Answer: (b) Temperature

5. A gas is compressed to half of its initial volume isothermally. The same gas is compressed again until the volume reduces to half through an adiabatic process. Then
(a) Work done during isothermal compression is more
(b) Work done is independent of the processes used for compression
(c) Work done is more during the adiabatic process
(d) Work done is dependent on the atomicity of the gas

Answer: (c) Work done is more during the adiabatic process

6. What is a necessary condition for a reaction to be spontaneous at all temperatures?
(a) ΔH < ΔG
(b) ΔG and ΔH should be positive
(c) ΔH = ΔG = 0
(d) ΔG and ΔH should be negative

Answer: (d) ΔG and ΔH should be negative

7. Which of the following process is used to do maximum work done on the ideal gas if the gas is compressed to half of its initial volume?
(a) Isothermal
(b) Isochoric
(c) Isobaric
(d) Adiabatic

Answer: (d) Adiabatic

8. Which of the following is the combination that is used in the formation of achromatic lenses?
(a) 1 convex and 1 plane mirror
(b) 2 convex lenses
(c) 1 convex and 1 concave lens
(d) 2 concave lenses

Answer: (c) 1 convex and 1 concave lens

9. What is the magnification produced by the plane mirror?
(a) Zero
(b) +1
(c) -1
(d) Between 0 and +∞

Answer: (b) +1

10. What happens to the refractive index on heating the liquid?
(a) Increases
(b) Decreases
(c) Remains unchanged
(d) Increases or decreases depending on the rate of heating

Answer: (b) Decreases

11. Rainbow is an example of which phenomenon?
(a) Refraction and scattering
(b) Refraction and total internal reflection
(c) Dispersion and reflection
(d) Dispersion and total internal reflection

Answer: (d) Dispersion and total internal reflection

12. What is hypermetropia?
(a) Bad vision due to age
(b) Short-sightedness
(c) Long-sightedness
(d) Formation of a layer on the eye

Answer: (c) Long-sightedness

13. Which of the following is created when trivalent impurities are added to a semiconductor?
(a) Free electrons
(b) Holes
(c) Bound electrons
(d) Valence electrons

Answer: (b) Holes

14. Which of these fluids has the highest viscosity?
(a) Water
(b) Honey
(c) Blood
(d) Air

Answer: (b)Honey

15. The element with the least mass per nucleon is
(a) Hydrogen
(b) Iron
(c) Helium
(d) Uranium

Answer: (b) Iron

16. Which of the following atomic particles have the least mass?
(a) Proton
(b) Electron
(c) Deuteron
(d) Neutron

Answer: (b) Electron

17. In which among the following, the speed of sound would be maximum?

(A) Dry air at 0°C
(B) Dry air at 30°C
(C) Humid air at 0°C
(D) Humid air at 30°C

Answer: (D) Humid air at 30°C

18. Which among the following provides potential energy to an object?

(A) Its momentum
(B) It’s position
(C) It’s acceleration
(D) It’s shape

Answer: (B) It’s position

19. Echoes are heard when we shout in an empty hall. But when the hall is full of people no echoes are heard why?

(A) Echoes are subdued in the noise of people
(B) Soft clothes of people absorb sound instead of reflecting it
(C) Destructive interference of sound takes place
(D) Excessive reverberations take place

Answer: (D) Excessive reverberations take place

20. What is the maximum height that can be attained by a projectile?

(A) equal to its maximum range
(B) one half of its maximum range
(C) one-fourth of its maximum range
(D) twice of its maximum range

Answer: (C) one-fourth of its maximum range

21. What is the absolute unit of power in c.g.s system?

(A) dyne
(B) erg
(C) watt
(D) erg s^-1

Answer: (D) erg s^-1

22. What is the phase of a vibrating particle at t = 0 known as?

(A) epoch
(B) eon
(C) path difference
(D) period

Answer: (A) epoch

23. How can a moving coil galvanometer be converted into a ammeter?

(A) by introducing shunt resistance in parallel
(B) by introducing shunt resistance in series
(C) by introducing large resistance in series
(D) None of the above

Answer: (A) by introducing shunt resistance in parallel

24. What is the SI unit of magnetic flux?

(A) teslas
(B) maxwell
(C) weber
(D) Newton

Answer: (C) weber

25. What is the S.I. unit of magnetic dipole moment?

(A) joule/tesla
(B) joule/metre
(C) tesla/metre
(D) Newton/metre

Answer: (A) joule/tesla

26. A falling drop of rain water ac-quires the spherical shape due to –
(A) Viscosity
(B) Surface Tension
(C) Atmospheric pressure
(D) Gravitational force
Answer – (B) Surface Tension

27. Gamma rays have greatest similarity with –
(A) α-rays
(B) β-rays
(C) X-rays
(D) U.V.-rays
Answer – (C) X-rays

28. Which physical quantity is measured in ‘siemens’?
(A) Electric potential
(B) Electrical conductance
(C) Magnetic flux
(D) Refractive index
Answer – (B) Electrical conductance

29. Sensation of sound persists in our brain for about –
(A) 0.001s
(B) 0.2s
(C) 0.1s
(D) 10s
Answer – (C) 0.1s

30. The surface tension of water on adding detergent to it –
(A) increases
(B) decreases
(C) no change
(D) becomes zero
Answer – (B) decreases

31. Lux is the SI unit of –
(A) intensity of illumination
(B) luminous efficiency
(C) luminous flux
(D) luminous intensity
Correct Answer – (A) intensity of illumination

32. Eclipses occur due to which optical phenomena?
(A) Reflection
(B) Refraction
(C) Rectilinear propagation
(D) Diffraction
Answer – (C) Rectilinear propagation

33. Pure water is bad conductor of electricity because it is –
(A) feebly ionized
(B) not volatile
(C) a very good solvent
(D) a non-polar solvent
Answer – (A) feebly ionized

34. Pycnometer is an instrument used to measure the –
(A) Density
(B) Intensity of solar radiation
(C) Intensity of earthquake
(D) High temperatures
Answer – (A) Density

35. Lamberts law is related to –
(A) Reflection
(B) Refraction
(C) Interference
(D) Illumination
Answer – (D) Illumination

36. Which of the following is used for regulated electric supply?
(A) Zener diode
(B) Junction diode
(C) Gun diode
(D) Tunnel diode
Answer – (A) Zener diode

37. The hydraulic brakes used in automobiles is a direct application of :
(A) Archimedes’ principle
(B) Toricellian law
(C) Bernoulli’s theorem
(D) Pascal’s law
Answer – (D) Pascal’s law

38. Solar energy is converted into chemical energy during –
(A) Transpiration
(B) Photosynthesis
(C) Diffusion
(D) Osmosis
Answer – (B) Photosynthesis

39. Alternating current is converted into direct current by a –
(A) Transformer
(B) Dynamo
(C) Oscillator
(D) Rectifier
Answer – (D) Rectifier

40. Which one of the following is used for sun glasses?
(A) Pyrex glass
(B) Flint glass
(C) Crooks glass
(D) Crystal glass
Answer – (C) Crooks glass

41. The unit of measurement of noise is –
(A) Decibel
(B) Hertz
(C) Amplifier
(D) Acoustics
Answer – (A) Decibel (The decibel (dB) is the unit used to measure the intensity of sound or noise level.)

42. Water has maximum density at _.
(A) 0 C
(B) -15 C
(C) 4 C
(D) 15 C
Answer – (C) 4 C

43. Safety fuse wire used in domestic electrical appliances is made of metal of low
(A) Resistance
(B) Melting point
(C) Specific gravity
(D) Conductance
Answer – (B) Melting point

44. Among the following materials sound travels fastest in –
(A) Steel
(B) Air
(C) Vacuum
(D) Water
Correct Answer – (A) Steel

45. The speed of light with the rise in the temperature of the medium :
(A) Increases
(B) Decreases
(C) Remains unaltered
(D) Drops suddenly
Answer – (C) Remains unaltered

46. Which of the following parts of the sunlight makes the solar cooker hot?
(A) Ultra violet
(B) Red light
(C) Infra red
(D) Cosmic rays
Answer – (C) Infra red

47. The image of an object formed on the retina of the eye is –
(A) virtual and upright
(B) virtual and inverted
(C) real and inverted
(D) Real and upright
Answer – (C) real and inverted

48. The electric charge is stored in a device called:
(A) Inductor
(B) Capacitor
(C) Resister
(D) Transformer
Answer – (B) Capacitor

49. When a bar magnet is cut into two equal halves, the pole strength of each piece
(A) becomes double
(B) becomes half
(C) becomes zero
(D) remains the same
Answer – (D) remains the same

50. The distance between node and adjacent antinodes is 30 cm. The wavelength is –
(A) 30 cm.
(B) 90 cm.
(C) 120 cm.
(D) 60 cm.
Answer – (D) 60 cm.

Also refer:

Important Multiple Choice Questions On Air Pollution

List of Important MCQs Of Physics For Competitive Exams

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