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 sentence is correct reason behind the blue color of ocean water?
[A] Water molecules absorb all other colors except blue
[B] Impurities in Sea water reflect the blue light
[C] Water molecules scatter the blue light
[D] None of the above
Show Answer
Correct Answer: C [Water molecules scatter the blue light]
Notes:
Water molecules scatter the blue light by absorbing the light waves and then rapidly re-emitting the light waves in different directions. That is why there are mostly blue wavelengths that are reflected back to our eyes.
2. On which of the following Inertia of an object depends ?
[A] Bulk
[B] Size
[C] Shape
[D] Mass
Show Answer
Correct Answer: D [Mass]
Notes:
Inertia is the resistance experienced by an object to any change in its velocity. This includes changes to the object’s speed, or direction of motion. Inertia of rest, Inertia of motion are the examples.
3. Fermi-Kurie plot is used for the study of which of the following?
[A] Alpha Decay
[B] Beta Decay
[C] Internal Conversion
[D] Cluster Decay
Show Answer
Correct Answer: B [Beta Decay]
Notes:
Fermi–Kurie plot is a graph developed by Franz N. D. Kurie and is used in studying beta decay. In this graph square root of the number of beta particles whose energy lie within a specific range, divided by the Fermi function, is plotted against beta-particle energy.
4. One joule of work is said to be done when__:
[A] a force of 1 dyne causes a displacement of 1 cm.
[B] a force of 1 dyne causes a displacement of 1 m.
[C] a force of 1 N causes a displacement of 1 cm.
[D] a force of 1 N causes a displacement of 1 m.
Show Answer
Correct Answer: D [ a force of 1 N causes a displacement of 1 m.]
Notes:
The joule is the unit of energy in the International System of Units. It is equal to the work done on an object when a force of one Newton acts on that object in the direction of the force’s motion through a distance of one meter. One joule of work is said to be done when a force of 1 N causes a displacement of 1 m.
5. Which among the following orbits are more prone to harms of space debris or space Junk in comparison to others?
[A] Polar Sun Synchronous Orbit
[B] Low Earth Orbit
[C] Geosynchronous orbit
[D] Geostationary Orbit
Show Answer
Correct Answer: D [ Geostationary Orbit]
Notes:
Low Earth Orbit (LEO) is more prone to space debris or space junk. This is because space debris is more concentrated in orbits closer to Earth. Most debris is within 2,000 km (1,200 miles) of Earth’s surface.
Space debris orbits the Earth at tremendous speeds, about 15,700 miles per hour (25,265 kph) in low Earth orbit. In the event of a collision, it could cause significant damage to a satellite or spacecraft.
Experts are concerned about the amount of space debris in regions that are too high to benefit from the cleansing effects of Earth’s atmosphere. They believe that if there is too much space junk in orbit, it could result in a chain reaction where more and more objects collide and create new space junk.
6. In recent times, the “dynamic brake system” is becoming popular in modern railways. The dynamic brake system coverts Kinetic energy to__:
[A] Potential energy
[B] Electricity
[C] Sound energy
[D] Magnetic energy
Show Answer
Correct Answer: B [ Electricity]
Notes:
Modern engines also have, additionally, dynamic brake system which works on the principle of converting kinetic energy of the moving train to electricity making the electric motors to work as generators.
7. Which among the following provides potential energy to an object?
[A] Its momentum
[B] It’s position
[C] It’s acceleration
[D] It’s shape
Show Answer
Correct Answer: B [ It’s position]
Notes:
The potential energy is defined as the energy that is stored in an object due to its position. Various types of potential energy include the gravitational potential energy (depends on its mass and its distance from the center of other object’s mass), the elastic potential energy, the electric potential energy.
8. Which of the following is the unit of Impulse?
[A] N
[B] Ns
[C] N/s
[D] Ns2
Show Answer
Correct Answer: B [ Ns ]
Notes:
The unit of impulse is Ns. Impulse = Force(N) x Time(s) Impulse can be defined as the integral of a force, F, over the time interval, t, for which it acts.
9. What is the angular acceleration of a body moving with constant angular velocity?
[A] equal to the angular velocity
[B] 1
[C] 0
[D] Can’t be determined
Show Answer
Correct Answer: C [0]
Notes:
The angular acceleration of a body moving with constant angular velocity is 0. Angular acceleration of an object in circular motion is defined as the time rate of change of its angular velocity.
10. The centripetal force and centrifugal force are ______:
[A] equal in magnitude and have same direction
[B] unequal in magnitude and have same direction
[C] equal in magnitude and have opposite direction
[D] unequal in magnitude and have opposite direction
Show Answer
Correct Answer: C [equal in magnitude and have opposite direction]
Notes:
The centripetal force and centrifugal force are equal in magnitude and have opposite direction. Centrifugal force can be regarded as the reaction of centripetal force.