UPSC General Science: Technology-1

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Today’s Topic : Technology-1

1. Assertion (A) : In a motion picture usually 24 frames are projected every second ever the whole length of film. Reason(R) : An image formed on the retina of eyes persists for about 0.2 seconds after the removal of stimulus.

a) Both A and R are true and R is the correct explanation of A.

b) Both A and R are true but R is not a correct explanation of A.

c) A is true but R false.

d) R is true but A false.

Ans:     C

Explanation:    A is true but R is false. In a motion picture, 24 frames are projected in a second which create the illusion of continuity. The visual sensation of a particular object as science persists for about 1/16 and after a change.

2. WIMAX is related to which one of the following:

a) Missile technology                b) Communication technology

c) Space technology                 d) None of these.

Ans:     B

Explanation:    WiMAX is an emerging technology for broadband wireless access. It promises very much high data rates, high reliability, good efficiency, and low cost. WIMAX enjoys strong industry support and standardization. Because of its low cost, it is used to provide broadband internet access to suburban rural areas and thus bridge the digital divide.

3. In order of their distances from which of the following planets lie between Mars and Uranus:

a) Saturn and Neptune               b) Saturn and Earth

c) Jupiter and Saturn                  d) Earth and Jupiter.

Ans:     C

Explanation:    As per distances from such Jupiter and Saturn lie in between Mars and Uranus. The solar system comprises the sun, eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune revolving around the sun. The direction of the planets in their revolution around the sun is from West to East. The earth is a third nearest planet the sun. The planets nearest to the earth is Venus. Sun-> Mercury-> Venus->Earth->Mars->Jupiter->Saturn->Uranus->Neptune.

4. A person sitting in a car which is at rest. The reaction from the road at each of four wheels of the car is R. When the car run on the straight level road, how will the reaction at either of the front wheel vary?

a) It shall depend on the material of the road               b) It will be greater than R

c) It will be less than R                                                 d) It will be equal to R

Ans:     D

Explanation:    The dynamic friction in any object is proportional to an instant reaction and it is less than static friction. When the car runs on a straight level of the road the reaction either of front wheel will be equal to R.

5. Optical fibre works on the principle of:

a) Interference               b) Scattering               c) Refraction                d) Total internal reflection

Ans:     D

Explanation:    Optical fibers works on the principle of total internal reflection. When the light is incident at small angle at one end, it gets refracted into the fiber and gets incident on the interface of the fibers and coating. The angle of critical is less than angle of incidence. So, the light suffers the internal reflection again and again till the angle of incidence being greater than the critical angle for the fiber.

6. When a mirror is rotated by an angle 0 the reflected ray will be rotate by:

a) 00               b) θ               c) 2 θ                d) None of these.

Ans:     C

Explanation:    For a given incident ray, if a plane mirror is rotated through a certain angle, then the reflected ray rotates through twice of that angle. So if a mirror is rotated by an angle θ, the reflected ray will rotate by 2 θ.

7. The internal reflection can take place when light travel from:

a) Air to water.               b) Diamond to glass               c) Air to glass               d) Water to glass

Ans:     B

Explanation:    Total internal reflection takes place when light travels from optically denser medium to optically rarer medium. (Refractive index for glass = 1.57, Refractive index of Diamond=2.45)

8. A ball is dropped from the top of a high building with a constant acceleration of 9.8m/s2. What will be its velocity after 3 seconds?

a) 9.8 m/s               b) 49.6 m/s               c) 23.9 m/s                   d) 29.4 m/s

Ans:     D

Explanation:    We know that

V = u + gt

(Where V is velocity, g is acceleration due to gravity and t is time)

V = 0 + 9.8 x 3

V = 29.4 m/s

9. Match the following list:

A) Force m/s2

B) Acceleration Joule

C) Velocity Newton

D) Work m/s.


A         B          C          D

a) 1         2          3          4

b) 3         1          4          2

c) 2         3          1          4

d) 4         3          2          1

Ans:     B


Force              –           Newton

Acceleration    –           m/s2

Work               –           Joule

Velocity           –           m/s

10. A noise level of 100 decibel would correspond to:

a) Noise from machine shop               b) Ordinary conversation

c)  sound from a noisy street               d) None of these.

Ans:     A

Explanation:    Loudness of sound is measured on the scale called decibel scale. The softest audible sound on the decibel scale is aero db. The noise level of 100 decibels would correspond to noise from a machine shop.