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 KirchoffтАЩs 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) ╬ФH < ╬ФG
(b) ╬ФG and ╬ФH should be positive
(c) ╬ФH = ╬ФG = 0
(d) ╬ФG and ╬ФH should be negative
Answer: (d) ╬ФG and ╬ФH 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 +тИЮ
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) ItтАЩs position
(C) ItтАЩs acceleration
(D) ItтАЩs shape
Answer: (B) ItтАЩs 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 тАУ
(A) Viscosity
(B) Surface Tension
(C) Atmospheric pressure
(D) Gravitational force
Answer тАУ (B) Surface Tension
27. Gamma rays have greatest similarity with тАУ
(A) ╬▒-rays
(B) ╬▓-rays
(C) X-rays
(D) U.V.-rays
Answer тАУ (C) X-rays
28. Which physical quantity is measured in тАШsiemensтАЩ?
(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 тАУ
(A) increases
(B) decreases
(C) no change
(D) becomes zero
Answer тАУ (B) decreases
31. Lux is the SI unit of –
(A) intensity of illumination
(B) luminous efficiency
(C) luminous flux
(D) luminous intensity
Correct Answer тАУ (A) intensity of illumination
32. Eclipses occur due to which optical phenomena?
(A) Reflection
(B) Refraction
(C) Rectilinear propagation
(D) Diffraction
Answer тАУ (C) Rectilinear propagation
33. Pure water is bad conductor of electricity because it is тАУ
(A) feebly ionized
(B) not volatile
(C) a very good solvent
(D) a non-polar solvent
Answer тАУ (A) feebly ionized
34. Pycnometer is an instrument used to measure the тАУ
(A) Density
(B) Intensity of solar radiation
(C) Intensity of earthquake
(D) High temperatures
Answer тАУ (A) Density
35. Lamberts law is related to тАУ
(A) Reflection
(B) Refraction
(C) Interference
(D) Illumination
Answer тАУ (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 тАУ (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 тАУ (D) Pascal’s law
38. Solar energy is converted into chemical energy during тАУ
(A) Transpiration
(B) Photosynthesis
(C) Diffusion
(D) Osmosis
Answer тАУ (B) Photosynthesis
39. Alternating current is converted into direct current by a тАУ
(A) Transformer
(B) Dynamo
(C) Oscillator
(D) Rectifier
Answer тАУ (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 тАУ (C) Crooks glass
41. The unit of measurement of noise is тАУ
(A) Decibel
(B) Hertz
(C) Amplifier
(D) Acoustics
Answer тАУ (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 тАУ (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 тАУ (B) Melting point
44. Among the following materials sound travels fastest in тАУ
(A) Steel
(B) Air
(C) Vacuum
(D) Water
Correct Answer тАУ (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 тАУ (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 тАУ (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 тАУ (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 тАУ (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 тАУ (D) 60 cm.
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