Competitive Exams Physics Objective Questions Part 7

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Q-1. For photoelectric emission, tungsten requires light of 2300 if light of 1800 wavelength is incident, then emission

(a) Takes place

(b) don՚t take place

(c) May or may not take place

(d) Depends on frequency.

Q-2. A type kept outside in sunlight bursts off after sometime because of

(a) Increase in pressure

(b) Increase in volume

(c) Both (a) and (b)

(d) None of these.

Q-3. For a wire of length 1, maximum change in length under streets condition is 2 mm. what is the change in length under same conditions when length of wire is halved?

(a) 1 mm

(b) 4 mm

(c) 2 mm

(d) 8 mm.

Q-4. Air is blown through a hole on a hole on a closed pipe containing liquid. Then the pressure will

(a) Increase on sides

(B) Increase downwards

(C) Increase in all directions

(D) Never increases.

Q-5. Light year is a unit of

(a) Time

(B) Speed

(C) Distance

(D) None of these

Q-6. A wire carrying current I and other carrying 2I in the same direction produces a magnetic field B at the midpoint. What will be the field when 2I wire is switched off?


(B) 2B

(C) B

(D) 4B

Q-7. What will be energy stored in a strained wire?





Q-8. If error in measurement of radius of sphere is 1 % , what will be the error in measurement of volume?

(a) 1 %


(C) 3 %

(D) 10 %

Q-9. Minimum numbers of unequal vectors which can give zero resultant are

(a) Two

(B) Three

(C) Four

(D) More than four

Q-10. A coin is dropped in a lift. It takes time to reach the floor when lift is stationary. It takes time when lift is moving up with constant acceleration. Then





Q-11. A large ship can float but a steel needle sinks because of

(a) Viscosity

(B) Surface tension

(C) Density

(D) None of these

Q-12. In a solenoid, if number of turns is doubled, then self-inductance will become

(a) Half

(B) Doubled

(C) Times

(D) Quadruped

Q-13. Core of transformer is made up of

(a) Soft icon

(B) Steel

(C) Iron

(D) Alnico

Q-14. Transformer is based upon the principle of

(a) Self induction

(B) Mutual Induction

(C) Eddy current

(D) None of these

Q-15. Refractive index of material is equal to tangent of polarizing angle. It is called

(a) Brewster՚s law

(B) Lambert՚s law

(C) Malus՚s law

(D) Brogg՚s law

Q-16. A car accelerates from rest at constant rate for 1st 10 s. and covers a distance x. It covers a distance y in next 10 s. at the same acceleration. Which of the following is true?





Q-17. The horizontal range of a projectile is 400 m. The maximum height attained by it will be

(a) 100 m

(B) 200 m

(C) 400 m

(D) 800 m

Q-18. What determines the nature of the path followed by the particle?

(a) Speed

(B) Velocity

(C) Acceleration

(D) None of these

Q-19. Which of the following is not an example of perfectly inelastic collision?

(a) A bullet fired into a block if bullet gets embedded into block

(B) Capture of electrons by an atom

(C) A man jumping on to a moving boat

(D) A ball bearing striking another ball bearing

Q-20. The length of second՚s pendulum is 1 m on earth. If mass and diameter of the planet is doubled than that of earth, then length becomes

(a) 1 m

(B) 2 m

(C) 0.5 m

(D) 4 m

Q-21. A hot and a cold body are kept in vacuum separated from each other. Which of the following cause decrease in temperature of the hot body?

(a) Radiation

(B) Convection

(C) Conduction

(D) Temperature remains unchanged

Q-22. When a tuning fork produces sound waves in air, which one of the following is same in the material of tuning fork as well as in air?

(a) Wavelength

(B) Frequency

(C) Velocity

(D) Amplitude

Q-23. A bomb explodes on the moon. How long will it take for the sound to reach the earth?

(a) 10 s

(B) 1000 s

(C) 1 day

(D) None of these

Q-24. What is the angle between the electric dipole moment and the electric field strength due to it on the equatorial line?




(D) None of these

Q-25. The city of the two plates of capacities are + 10V and -10V. The charge on one of the plates is 40 C. The capacitance of the capacitor is

(a) 2 F

(B) 4 F

(C) 0.5 F

(D) 0.25 F

Q-26. To draw maximum current from a combination of cells, how should the cells be grouped?

(a) Series

(B) Parallel

(C) Mixed

(D) Depends upon the relative values of external and internal resistance

Q-27. A wire is cut into 4 pieces, which are put together by sides to obtain one conductor. If the original resistance of wire was R, the resistance of the bundle will be





Q-28. What happens to the fringe pattern when the Young՚s double slit experiment is performed in water instead of air?

(a) Shrinks

(B) Disappear

(C) Unchanged

(D) Enlarged

Q-29. An object is placed at a distance equal of focal length of convex mirror. If the focal length of the mirror be f, then the distance of the image from the pole of the mirror is

(a) Less than f

(B) Equal to f

(C) More than f

(D) Infinity

Q-30. Ability of the eye to see object at all distances is called

(a) Binocular vision

(B) Myopia

(C) Hypermetropia

(D) Accommodation

Q-31. The magnitude of saturation photoelectric current depends upon

(a) Frequency

(B) Intensity

(C) Work function

(D) Stopping potential

Q-32. Which of the following is most unstable?

(a) Electrons

(B) Protons

(C) Neutrons

(D) - particle

Q-33. After 2 hrs, of initial amount of a certain radioactive isotope remains undecided. The half-life of the isotope is

(a) 15 min

(B) 45 min

(C) 30 min

(D) 60 min

Q-34.10 g of ice at C is mixed with 100 g of water at C. What is the resultant temperature of mixture?

(a) C

(B) C

(C) C

(D) C

Q-35. An atomizer is based on the application of

(a) Torricelli՚s theorem

(b) Bernoulli՚s theorem

(c) Archimedes principle

(d) Principle of continuity

Q-36. ‘Pascal-second’ has the dimensions of

(a) Force

(b) Energy

(c) Pressure

(d) Coefficient of viscosity

Q-37. Consider the following equation of Bernoulli՚s theorem.

The dimensions of are same as that of which of the following?

(a) Thrust

(b) Pressure

(c) Angle

(d) Viscosity

Q-38. What effect occurs on the frequency of a pendulum it is taken from the earth surface to deep into a mine?

(a) Increases

(b) Decreases

(c) First increases then decreases

(d) No effect

Q-39. The volume of a cube in is equal to the surface area of the cube in The volume of the cube is





Q-40. An ice block contains a glass ball when the ice melts within the water containing vessel. The level of water.

(a) Rises

(b) Falls

(c) Unchanged

(d) First rises and then falls.