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. Crystals of which of the following naturally-occuring substance exhibits both ‘pyroelectric’ and ‘piezoelectric’ properties making it versatile for application in the field of electronics?
[A] Quartz
[B] Mica
[C] Topaz
[D] grapite
Show Answer
Correct Answer: A [Quartz]
Notes:
Quartz crystals have piezoelectric properties: they develop an electric potential upon the application of mechanical stress. An early use of this property of quartz crystals was in phonograph pickups. A common piezoelectric use of quartz today is as a crystal oscillator. The quartz clock is a familiar device using the mineral. Quartz is also strongly pyroelectric. Temperature changes create positive and negative charges within the crystal.
2. The X-ray crystallography mainly uses which among the following properties of electromagnetic radiation?
[A] Reflection
[B] Diffraction
[C] Interference
[D] Refraction
Show Answer
Correct Answer: B [ Diffraction]
Notes:
X-ray crystallography helps to determine the atomic and molecular structure of a crystal. The crystalline structure performs the diffraction and it causes a beam of incident X-rays to diffract into many specific directions.
3. 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
4. The branch of mechanics which deals with the study of motion of material objects without taking into account the factors which cause motion is called as:
[A] Statics
[B] Kinematics
[C] Dynamics
[D] None of the above
Show Answer
Correct Answer: B [Kinematics]
Notes:
The branch of mechanics which deals with the study of motion of material objects without taking into account the factors which cause motion is called as Kinematics. The branch of mechanics which deals with the study of motion of material objects taking into account the factors which cause motion is called as Dynamics. The branch of mechanics which deals with the study of material objects at rest is called as Statics.
5. Which of the following is correct about Kinetic energy during the projectile motion?
[A] it is minimum at the point of projection
[B] it is minimum at the highest point
[C] it is maximum at the highest point
[D] it is minimum at the point of reaching the ground
Show Answer
Correct Answer: B [it is minimum at the highest point]
Notes:
The Kinetic energy of an object is maximum at the point of projection or at the point of reaching the ground. It is minimum at the highest point.
6. Which of the following is NOT correct about Vectors addition?
[A] Vectors addition is associative
[B] Vectors addition is commutative
[C] Vectors of different natures can be added
[D] None of the above
Show Answer
Correct Answer: C [Vectors of different natures can be added]
Notes:
Vectors addition is associative and commutative. But vectors of the same nature alone can be added. Example: a Force vector cannot be added to velocity vector as they are of different nature.
7. What is the apparent weight of the person when the elevator is accelerating downwards?
[A] equal to the actual weight
[B] greater than the actual weight
[C] less than the actual weight
[D] 0
Show Answer
Correct Answer: C [less than the actual weight]
Notes:
The apparent weight of the person becomes less than the actual weight when the elevator is accelerating downwards. The apparent weight of the person becomes more than the actual weight when the elevator is accelerating upwards.
8. On which of the following quantities, Work done does not depend?
[A] Force applied
[B] Displacement
[C] Time
[D] Depends on all of the above
Show Answer
Correct Answer: C [Time]
Notes:
Work done does not depend on the time for which the force was applied. Work done is only dependant on the force and displacement. Time is involved in the case of Power only
9. The Universal Gravitational Constant for two bodies is dependent on which of the following?
[A] Nature of the bodies
[B] Size of the bodies
[C] Nature of medium between the bodies
[D] None of the above
Show Answer
Correct Answer: D [None of the above]
Notes:
The value of Universal Gravitational Constant is same throughout the universe. It is independent of nature of the bodies, size of the bodies and nature of medium between the bodies.
10. What is the unit of Stress?
[A] N/m
[B] Kg/m
[C] Nm
[D] It has no units
Show Answer
Correct Answer: A [N/m]
Notes:
If an external force F is applied on the area A of a body then, Stress is given by Force/Area Units of Stress: S.I unit: N / m C.g.s unit: dyne / cm
