# RRB NTPC Physics quiz for Stage I : 01/04/2019

## RRB NTPC Physics quiz for Stage I

Railway/SSC JE Physics quiz for  (Phase I), RRB NTPC, SSC various exams and other competitive exams.

Q1. Why does ice covered in sawdust not melt quickly?

(a) Sawdust does not allow the air to touch the ice

(b) The water is absorbed by sawdust

(c) Sawdust is a bad conductor of heat

(d) Sawdust is good conductor of heat

Q2. The washing machine works on the principle of ____________

(a) Dialysis

(b) Diffusion

(c) Reverse osmosis

(d) Centrifugation

Q3. An air bubble in water will act like a:

(a) Convex mirror

(b) Convex lens

(c) Concave mirror

(d) Concave lens

Q4. The frequency of direct current is ____________

(a) Zero

(b) 50 HZ

(c) 60 HZ

(d) 100 HZ

Q5. If a body is moving on a circular path, what is its average velocity if it completes one cycle in one second?

(a) Average velocity depends upon time taken to complete one cycle

(b) One

(c) Average velocity is same as average speed

(d) Zero

Q6. Telephone exchange was invented by?

(b) Joseph Priestley

(c) Petrache Poenaru

(d) James Leonard Plimpton

Q7. What will happen to the force between the two positive charges which are released after being held near each other?

(a) Force will increase

(b) Force will decrease

(c) Force will stay the same

(d) Force first increases to reach maximum before starting to decrease

Q8. Which device is used to measure earthquakes?

(a) Endoscope

(b) Thermometer

(c) Sonograph

(d) Seismograph

Q9. Sea seems blue due to-

(a) Excess deepness

(b) Reflection of sky and scattering of light by the drops of water

(c) Blue colour of water

(d) Upper layer of water

Q10. Who invented PlayStation?

(a) Wright brothers

(b) Reynold B. Johnson

(c) Assen Jordanoff

(d) Ken Kutaragi

## Solution

Ans.1.(c)

Exp. Saw dust is used to cover ice because it is poor conductor of heat. It did not let the ice melt quickly, as it does not transfer the heat of the surrounding to the ice.

Ans.2.(d)

Exp. The washing machine works on the principle of Centrifugation.

Ans.3.(d)

Exp. Air is optically rarer than water, the ray of light bends away from the normal at the point of incidence when moving from water to air while it bends towards the normal while moving from air to water. It is clearly visible that the air bubble acts as a DIVERGING LENS (concave lens) in water.

Ans.4.(a)

Exp. DC implies no changes in value. Frequencies of signals are defined by how many changes per time, e.g. 60 cycles per second. In case of DC with there are 0 changes per second. Hence the frequency of DC is zero.

Ans.5.(d)

Exp. When a body is moving in a circular path, its average velocity when it complete one cycle in one second is zero.

Ans.6.(a)

Exp. Telephone exchange was invented by Tivadar Puskas.

Ans.7.(b)

Exp. Two Positive charges will repel to each other so the force will decrease between two positive charge.

Ans.8.(d)

Exp. A Seismometer is an instrument that measures motion of the ground, caused by, for example, an earthquake, a volcanic eruption, or the use of explosives.

Ans.9.(b)

Exp. “The ocean looks blue because red, orange and yellow (long wavelength light) are absorbed more strongly by water than is blue (short wavelength light). So when white light from the sun enters the ocean, it is mostly the blue that gets returned.

Ans.10.(d)

Exp. PlayStation was the brainchild of Ken Kutaragi, a Sony executive who had just finished managing one of the company’s hardware engineering divisions at that time and would later be dubbed as “The Father of the PlayStation”.

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