61. If an object, on a free fall from a certain height, reaches the ground in 1 second, what is its velocity on the impact with the ground?
1. 4.9 m/s
2. 9.8 m/s
3. 14.7 m/s
4. 19.6 m/s
Option “2” is correct. If an object, on a free fall from a certain height, reaches the ground in 1 second, its velocity on the impact with the ground 9.8 m/s.
62. What is the angle between centripetal acceleration and tangential acceleration?
1. 90°
2. 45°
3. 0°
4. 180°
Option “1” is correct. The angle between centripetal acceleration and tangential acceleration is 90°.
63. Rectifiers convert _____.
1. High voltage to low voltage
2. Low voltage to high voltage
3. AC to DC
4. DC to AC
Option “3” is correct. A rectifier is an electrical device composed of one or more diodes that converts alternating current (AC) to direct current (DC).
64. Name the first Indian who got Nobel Prize in physics.
1. C K Naidu
2. Rangnath Mishra
3. Amartya Sen
4. C V Raman
Option “5” is correct. The Nobel Prize in Physics 1930 was awarded to Sir Chandrasekhara Venkata Raman “for his work on the scattering of light and for the discovery of the effect named after him.
65. Which physical quantity is measured in ‘siemens’?
1. Electric potential
2. Electrical conductance
3. Magnetic flux
4. Refractive index
Option “2” is correct. The Siemens (symbol S) is the derived unit of electric conductance.
66. Who invented Universal Standard Time?
1. Enrico Fermi
2. Adolf Gaston Eugen Fick
3. Sandford Fleming
4. Benoit Fourneyron
Option “3” is correct. Universal Standard time, as originally proposed by Scottish-Canadian Sir Sandford Fleming in 1879, divided the world into twenty-four time zones, each one covering 15 degrees of longitude.
67. _____________________ states that the total current entering a junction is equal to the total current leaving the junction.
1. Lenz’s Law
2. Hooke’s Law
3. Ohm’s Law
4. Kirchhoff’s First Law
Option “4” is correct. Kirchhoff’s First Law states that the total current entering a junction is equal to the total current leaving the junction. In other words, the algebraic sum of currents at a junction is zero.
68. Acceleration due to gravity on a planet decreases with ______.
1. Decrease in radius of the planet
2. Increase in mass of the planet
3. Decrease in mass of the body
4. Increase in altitude from surface of the planet
Option “4” is correct. Acceleration due to gravity on a planet decreases with increase in altitude from surface of the planet.
69. Instrument for measuring wind velocity is called –
Option “1” is correct. Rakesh Sharma was the first Indian to travel in Space. He was born on 13th January 1949 in Punjab, India. He flew to the Salyut 7 Space Station.
