Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
1. Which among the following waves are used in the gemstone industry to change white topaz into blue topaz?
[A] X-Rays
[B] Gamma Rays
[C] Alpha Radiation
[D] Beta Radiation
Show Answer
Correct Answer: B [Gamma Rays]
Notes:
Gamma rays is commonly used in gemstone industry to change white topaz into blue topaz. Because white topaz is heat-treated to turn into blue topaz, the value of blue topaz is often decreased.
2. In which of the following conditions, a Balloon filled with a gas such as Hydrogen will tend to rise up?
[A] If the buoyant force exerted by the air on a balloon is greater than the weight of the balloon
[B] If the buoyant force exerted by the air on a balloon is less than the weight of the balloon
[C] If the buoyant force exerted by the air on a balloon is equal to the weight of the balloon
[D] If the density of the air is greater than the density of the gas filled in balloon
Show Answer
Correct Answer: A [ If the buoyant force exerted by the air on a balloon is greater than the weight of the balloon]
Notes:
A Balloon filled with a gas such as Hydrogen gas is much lighter in weight than the weight of air displaced by it. So the buoyant force exerted by the air on a balloon is greater than the weight of the balloon. The hydrogen gas which is lighter than air enables the balloon to float.
3. Linear momentum can be described in which of the following units?
[A] kgm2/s2
[B] kg/ms2
[C] kg/ms
[D] kgm/s
Show Answer
Correct Answer: D [ kgm/s ]
Notes:
The SI unit of Linear Momentum is kg m/s Linear Momentum = Mass(kg) x Velocity (m/s) Linear Momentum is the quantity of motion of a moving body. Dimensional Formula of Linear Momentum is [M1 L1 T-1]
4. Which of the following is true about displacement of an object?
[A] It is always equal to the distance travelled by the object
[B] It can be less than the distance travelled by the object
[C] It can be greater than the distance travelled by the object
[D] It always less than the distance travelled by the object
Show Answer
Correct Answer: B [It can be less than the distance travelled by the object]
Notes:
The displacement is the shortest distance between the initial and final position of an object in the given time. The displacement of an object is a vector quantity. It can be less than or equal to the distance but can never be greater than the distance travelled by that object
5. A projectile will achieve maximum horizontal range at which angle?
[A] 90°
[B] 60°
[C] 45°
[D] 30°
Show Answer
Correct Answer: C [45°]
Notes:
A projectile will achieve maximum horizontal range when it is projected at an angle of 45°. This concept of maximum horizontal range is used by athletes in long jump, javelin throw, cricket ball throw etc
6. The work done by a variable force is given by:
[A] area under the force curve and the displacement axis
[B] square of the area under the force curve and the displacement axis
[C] natural log of the area under the force curve and the displacement axis
[D] twice the area under the force curve and the displacement axis
Show Answer
Correct Answer: A [area under the force curve and the displacement axis]
Notes:
The work done by a variable force is given by the area under the force curve and the displacement axis. W = Area ABCDA
7. Which of the following is the unit of Strain?
[A] Newton
[B] Kg
[C] Watt
[D] None of the above
Show Answer
Correct Answer: D [None of the above]
Notes:
As Strain is the ratio of two like quantities, it has no dimensions and units. Strain = Change in configuration/Original configuration
8. Which of the following has no effect on the pressure beneath the surface of a liquid?
[A] Area of the liquid surface
[B] Density of the liquid
[C] Strength of the gravitational field
[D] Depth of the liquid
Show Answer
Correct Answer: A [Area of the liquid surface]
Notes:
Pwater = ⍴gh It is clear from the above formula that water pressure only depends on density of water, gravitational acceleration and height of water column.
9. What happens to the liquid in a capillary of insufficient length?
[A] liquid overflows from the upper end like a fountain
[B] liquid tickles along the vertical sides of the tube
[C] liquid does not rise at all
[D] None of the above
Show Answer
Correct Answer: D [None of the above]
Notes:
In case of capillary of insufficient length, the liquid will neither overflow from the upper end like a fountain nor will it tickle along the vertical sides of the tube. The liquid after reaching the upper end will increase the radius of its meniscus without changing nature.
10. Which is the effect of increase in impurities on the surface tension of the liquid?
[A] It increases
[B] It decreases
[C] It may increase or decrease
[D] No change
Show Answer
Correct Answer: C [It may increase or decrease]
Notes:
The presence of impurities considerably affect the force of surface tension, depending upon the degree of contamination. A highly soluble substance like sodium chloride when dissolved in water, increases the surface tension of water. But the sparingly soluble substances like phenol when dissolved in water, decreases the surface tension of water.
