What is the relation between wavelength, frequency and velocity ?

Answer: Option B

Explanation:

David Hughes of USA invented Microphone in 1878,

Machine Gun was invented by Richard Gatling of USA in 1861,

Microscope was invented by Z. Jansen of Netherlands in 1590,

Motorcycle was invented by Edward Butler of England in 1884.

Answer: Option C

Explanation:

Ammeter - Measures strength of electric current.

Audiometer - Measures intensity of sound.

Anemometer - Measures force and velocity of wind and directions.

Answer: Option A

Explanation:

K. Macmillan of Scotland invented Bicycle in 1839.

Barometer was invented by E. Torricelli of Italy in 1644.

Calculating Machine was invented by Pascal of France in 1642.

Centigrade Scale was invented by A. Celsius of France in 1742.

Answer: Option C

Explanation:

Kelvin is used to measure Temperature,

Candela is used to measure Intensity of flame,

Steredian is used to measure Solid Angle.

Answer: Option D

Explanation:

These rays heat the materials on which they fall.