Question Detail

What is refractive index ?

it is defined as the ratio of speed of light in the medium to the speed of light in vacuum.
it is defined as the ratio of speed of light in vacuum to the speed of light in the medium .
it is defined as the product of speed of light in medium and in vacuum.
None of above

Answer: Option B

1. Which instrument is used to measure sound under water ?

Hygrometer
Hygroscope
Hypsometer
Hydrophone

Answer: Option D

Explanation:

Hygrometer - is used to measure level of humidity,

Hygroscope - shows the changes in atmospheric humidity,

Hypsometer - is used to determine the boiling points of liquids.

2. Alexander Graham Bell invented

Telephone
Telescope
Television
Tank

Answer: Option A

Explanation:

Alexander Graham Bell of USA invented Telephone in 1876,

Telescope was invented by Hans Lippershey of Netherlands in 1608,

Television was invented by John Logie Bared of Scotland in 1926,

Tank was invented by Sir Ernest Swington of England in 1914.

3. Thomas Alva Edison invented

Cinema
Cine Camera
Computer
Cinematograph

Answer: Option D

Explanation:

Thomas Alva Edison of USA invented Cinematograph in 1891,

Cinema was invented by A.L. and J.L. Lumiere of France in 1895,

Cine Camera was invented by Friese-Greene of Britain in 1889,

Computer was invented by Charles Babbage of Britain in 1834, he is also known as Father of Computer.

4. Which instrument is used to measure strength of direct current ?

Stroboscope
Streoscope
Tangent Galvanometer
Tachometer

Answer: Option C

Explanation:

Stroboscope - is used to view rapidly moving objects,

Streoscope - is used to view two dimensional pictures,

Tachometer - is used to determine rotational speed of a shaft (used in aeroplanes and motor boats).

5. The incident ray, reflected ray and normal to the reflecting surface at the incident point all never lie in same plane.

True
False

Answer: Option B