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. In which of the following light produces image focus in front of the retina?
[A] Presbyopia
[B] Myopia
[C] Hyperopia
[D] Hypertropia
Show Answer
Correct Answer: B [Myopia]
Notes:
The inability to see the distant objects clearly and distinctly is called short sightedness or Myopia. This defect arises when the image is formed infront of the retina. A short sighted person can see near objects clearly. This may arise due to either excessive curvature of the cornea or elongation of the eyeball. This defect is corrected by wearing glasses with a concave lens.
The inability to see near objects clearly and distinctly is called long sightedness or Hypermetropia. This defect arises when the image is formed behind the retina. This defect may arise due to shortening of eye ball. A long sighted person can see the distant objects clearly. This defect is corrected by wearing spectacles with convex lens (converging) of appropriate focal length. A converging lens will correct this defect by converging the incoming rays so that the image is formed on the retina.
2. When a tubelight breaks, a cracking sound is produced because ____?
[A] Pressure inside the lamp is less than atmospheric pressure
[B] Pressure inside the lamp is more than atmospheric pressure
[C] The lamp is filled with reactive gases
[D] The lamp is filled with mercury vapour
Show Answer
Correct Answer: A [Pressure inside the lamp is less than atmospheric pressure ]
Notes:
A fluorescent lamp tube is filled with a gas containing low pressure mercury vapor and argon, xenon, neon, or krypton. The pressure inside the lamp is around 0.3% of atmospheric pressure.
3. For any object on the surface of earth, which among the following properties will be directly proportional to each other?
[A] It’s acceleration and it’s mass
[B] It’s mass and it’s weight
[C] It’s weight and it’s acceleration
[D] It’s speed and it’s velocity
Show Answer
Correct Answer: B [ It’s mass and it’s weight]
Notes:
The weight of an object and its mass are directly proportional. For a given gravitational field strength, the greater the mass of the object, the greater its weight.
4. If the time taken in an echo is 5 seconds, which among the following will be the approximate distance of the object from source of sound? (assume normal room temperature at 20°C)
[A] 1715 meters
[B] 1256 meters
[C] 857 meters
[D] 554 meters
Show Answer
Correct Answer: C [ 857 meters]
Notes:To calculate the distance of the object from the source of sound based on the time taken for the echo, we can use the formula for distance traveled by sound:
Distance = (Speed of Sound × Time) / 2
The speed of sound in air at normal room temperature (20°C) is approximately 343 meters per second (m/s).
Given that the time taken in the echo is 5 seconds, we can plug the values into the formula:
Distance = (343 m/s × 5 s) / 2 Distance = 1715 meters / 2 Distance ≈ 857.5 meters
So, the approximate distance of the object from the source of sound is approximately 857.5 meters.
5. Due to which of the following phenomena, the coloured glass appears white when crushed into fine powder?
[A] Total Internal Reflection
[B] Diffraction
[C] Scattering
[D] Refraction
Show Answer
Correct Answer: C [ Scattering]
Notes:
When the glass is crushed into fine powder the light incident is totally scattered without the absorption so due to the composite light crushed glass appears white.
6. kg m2is the unit of which of the following physical quantities?
[A] Linear Momentum
[B] Angular Momentum
[C] Angular Impulse
[D] Moment of Inertia
Show Answer
Correct Answer: D [ Moment of Inertia ]
Notes:
kg m2is the unit of Moment of Inertia. The moment of inertia is a physical quantity which describes how easily a body can be rotated about a given axis. It is a rotational analogue of mass. Moment of Inertia = mass x (radius of gyration)2
7. 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
8. The forces acting at a point are called as:
[A] Collinear forces
[B] Coplanar forces
[C] Concurrent forces
[D] Unit forces
Show Answer
Correct Answer: C [Concurrent forces]
Notes:
The forces which are acting at a point are called as concurrent forces. Note: When concurrent forces in equilibrium act on a body, the state of the body shall remain unchanged i.e. if the body is at rest, it will continue to be at rest. Similarly, a body will continue to move uniformly along the same straight line, if concurrent forces in equilibrium are applied on the body.
9. When one body is actually moving over the surface of other body, the friction is known as:
[A] Kinetic friction
[B] Limiting friction
[C] Static friction
[D] Negative friction
Show Answer
Correct Answer: A [Kinetic friction]
Notes:
When one body is actually moving over the surface of other body, the friction is known as Kinetic friction. It is also known as dynamic friction.
10. What is the rate of acceleration produced by 1 dyne force acting on a body of mass 1 gram?
[A] 9.8 m s-2
[B] 1 m s-2
[C] 1 cm s-2
[D] 9.8 cm s-2
Show Answer
Correct Answer: C [1 cm s-2]
Notes:
One dyne force is that much force which produces an acceleration of 1 cm s-2 in a body of mass one gram. 1 dyne = 1 g cm s-2 Also, 1 N = 105 dyne
