Physics (Part-III) (Railway)

Total Questions: 50

11. The change in the kinetic energy of an object is equal to the total force exerted on that object. This statement is related to- [RRB RPF/RPSF SI Exam, 11.01.2019 Shift-II]

(1) Conservation of Mechanical energy
(2) Work done by different forces
(3) Work-energy Theorem
(4) Theory of conservation of Energy

Correct Answer: (3) Work-energy Theorem

Solution:The principle of work and kinetic energy (also known as the work-energy theorem) states that the work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle. This definition can be extended to rigid bodies by defining the work of the torque and rotational kinetic energy. The work-energy theorem can be derived from Newton's second law.

12. Which of the following is formed by total electric decomposition of water in nuclear reactors and is used as a moderator [RRB RPF/RPSF SI Exam, 11.01.2019 Shift-II]

(1) Hard water
(2) Soft water
(3) Permanent hard water
(4) Heavy water

Correct Answer: (4) Heavy water

Solution:Heavy water (deuterium oxide) is a form of water that contains a larger than normal amount of the hydrogen isotope deuterium rather than the common hydrogen-I isotope that makes up most of the hydrogen in normal water. The presence of deuterium gives the water different nuclear properties. The coolant is a liquid or gas that removes the heat from the core and produces steam to drive the turbines. In reactors using either light water or heavy water, the coolant also serves as the moderator.

13. Which method is used to measure the long distance? [RRB RPF/RPSF SI Exam, 11.01.2019 Shift-III]

(1) Parallax Method
(2) Contact Method
(3) Root Method
(4) Derivative Method

Correct Answer: (1) Parallax Method

Solution:Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines, Parallax also affects optical instruments such as rifle scopes, binoculars, microscopes, and twin - lens reflex cameras that view objects from slightly different angles.

14. Among given two medium, the angle of incidence from one medium becomes 90° of the corrosponding angle of reflection of rarrer medium, then it is called....... [RRB RPF/RPSF SI Exam, 11.01.2019 Shift-III]

(1) Critical angle
(2) Angle of incidence
(3) Mirror angle
(4) Common angle

Correct Answer: (1) Critical angle

Solution:The critical angle is the angle of Incidence where the angle of refraction is 90°. The light must travel from an optically more dense medium to an optically less dense medium.

15. Which diode is extensively used in the form of electric stabilizer? [RRB RPF/RPSF SI Exam, 11.01.2019 Shift-III]

(1) Light emitting diode
(2) Tunnel diode
(3) Solar diode
(4) Zener diode

Correct Answer: (4) Zener diode

Solution:A Zener diode is a type of diode that allows current to flow not only from its anode to its cathode, but also in the reverse direction, when the Zener voltage is reached. The Zener diode is üsed for regulating the voltage. It provides the constant voltage from the fluctuating voltage source to the load.

16. Which of the following Circuit is used for measuring irregular resistance? [RRB RPF/RPSF SI Exam, 11.01.2019 Shift-III]

(1) Bridge rectifier
(2) Jenner diode
(3) Wheatstone bridge
(4) Transistor

Correct Answer: (3) Wheatstone bridge

Solution:A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of the circuit is its ability to provide extremely accurate measurements.

17. What do orbitals with the same energy represent? [RRB RPF/RPSF SI Exam, 12.01.2019 Shift-II]

(1) Degenerate
(2) Steady-state
(3) Regenerate
(4) Excited state

Correct Answer: (1) Degenerate

Solution:Electron orbitals that have the same energy levels are calleddegenerate orbitals. When assigning electrons to orbitals in determining electron configurations, the Aufbau principle states that lower energy orbitals are filled before higher energy orbitals. As per Hund's rule, the degenerate orbitals are filled evenly before they move to higher energy levels.

18. What is the value of electric field equal to? [RRB RPF/RPSF SI Exam, 13.01.2019 Shift-II]

(1) electric speed
(2) electrical conductivity
(3) Electric dipole
(4) Electric flux

Correct Answer: (4) Electric flux

Solution:Electric flux is the rate of flow of the electric field through a given area. Electric flux is proportional to, the number of electric field lines going through a virtual surface.

19. What is the force exerted by gravity on an object called? [RRB RPF/RPSF SI Exam, 13.01.2019 Shift-II]

(1) Displacement
(2) Load
(3) Mass
(4) Velocity

Correct Answer: (2) Load

Solution:The weight of an object is defined as the force of gravity on the object and may be calculated as the mass times the acceleration of gravity, w = mg. Since the weight is a force, its SI unit is the newton

20. The pseudo force acting to deflect or push an object out of the center is called- [RRB RPF/RPSF SI Exam, 13.01.2019 Shift-III]

(1) Current force
(2) Centripetal force
(3) Centrifugal force
(4) Frictional force

Correct Answer: (3) Centrifugal force

Solution:Centripital force is defined as, the force that is necessary to keep an object moving in a curved path and that is directed inward toward the center of rotation, while centrifugal force is defined as the apparent force that is felt by an object moving in a curved path that acts outwardly away from the center of rotation.

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