Ans: Denis Papin (France)
F The basic principle of pressure cooker is that when pressure increases boiling point also increases. Inside a pressure cooker, boiling point of water is 122°C.
2. Who discovered Kaleidoscope?
Ans: David Brewster
F Kaleidoscope produces multiple reflections and it is based on the total internal reflection of light
3. Who invented Hydrometer?
Ans: Antoine Baume (France)
F It is an instrument used to measure density of liquids. Hydrometer used for measuring density of milk is called Lactometer.
4. Who invented Telescope?
Ans: Hans Lippershey (Netherlands)
F Telescope is used to see distant objects. Two convex lenses are used for making a telescope. Convex lens which comes in front of objects is called objective lens and that comes in front of the eye of the observer is called eyepiece lens
F Galileo used Telescope for viewing heavenly bodies. The modified form of Telescope developed by Galileo for astronomical purpose is called Astronomical Telescope.
5. Who measured the charge of an electron at first?
Ans: Robert Andrews Millikan
F By his oil drop experiment he measured the charge of an electron and got Nobel Prize in Physics at 1923.
6. Who invented simple microscope?
Ans: Anton van Leeuwenhoek
F Compound microscope- invented by Hans and Zacharias Janssen
F Modern Compound microscope - invented by Johannes Kepler
F Reflecting microscope - invented by Giovanni Amici
F Electron microscope -- invented by Ernst Rush
7. Who invented ophthalmoscope?
Ans: Hermann Helmholtz
F He measured the speed of a nerve impulse at first.
8. Who invented IC Chips?
Ans: Jack Kilbi
F IC Chip is a small semiconductor chip which contains resistors, capacitors, transistors etc.
9. Who discovered Calorie meter?
Ans: Laplace and Lavoiseue
F Calorie meter is an instrument used to measure the heat energy.
10. Who discovered superconductivity?
Ans: Camerling Onnes (Netherlands)
F Superconductivity is the state at which resistance becomes zero and conductance becomes maximum.
F First made superconductor - Mercury.
11. Who invented Thermometer?
Ans: Galileo
F Galileo used water as liquid in thermometer.
12. Who developed dynamo or generator?
Ans: Michael Faraday (England)
F A generator converts mechanical energy to electric energy. Electromagnetic induction is the basic principle of working of a dynamo.
F Michael Faraday discovered electromagnetic induction and he is known as father of electricity.
13. Who invented Barometer?
Ans: E Torricelli (Italy)
F Barometer is used to measure atmospheric pressure. It uses mercury as liquid.
14. Who developed LASER first?
Ans: Theodore Maimann (USA)
F LASER is a monochromatic and coherent light source. The first developed LASER by Maimann was Ruby LASER. He used Chromium metal for developing it.
15. Who discovered X-rays?
Ans: Roentgen
F X-rays are electromagnetic waves. They can penetrate through bones.
F Roentgen won the first Nobel Prize in physics for this discovery.
16. Who invented transistors?
Ans: John Bardeen, W Brattain and William Shockley (USA)
F Transistors are used for voltage or current amplification purposes.
17. Who invented RADAR?
Ans: Alfred H. Taylor and Leo C. Young.
F RADAR-Radio Detection and Ranging.
18. Who invented transformers?
Ans: William Stanley
F Transformer increases or decreases AC Voltage. There are two types of transformers, step up and step down. Transformers are based on electromagnetic induction.
19. Who invented radiometer?
Ans: Sir William Crookes.
20. Who invented Thermos flask or Dewar flask?
Ans: Sir James Dewar
21. Who discovered positrons?
Ans: Carl David Anderson
F In 1932 he discovered positrons in cosmic radiations. He also discovered mu-mesons in 1939.
22. Who first constructed X-ray spectrometer?
Ans: Sir William Henry Bragg
F X-ray spectrometer is used to measure the wavelength of X-rays.
23. Who first developed a torsion balance by which the density and mass of the earth is calculated?
Ans: Henry Cavendish
F He developed a torsion balance in 1798. He also discovered hydrogen gas and synthesized water by exploding hydrogen in oxygen.
24. Who invented MASER?
Ans: Charles H. Towns
F MASER is the Microwave Amplification by Stimulated Emission of Radiation.
