Option “3” is correct. Rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The process is known as rectification, since it “straightens” the direction of current.
142. Which device is used to measure the depth of ocean?
Option “3” is correct. Fathometer is a depth finder that uses sound waves to determine the depth of water.
143. Barograph was invented by –
1. Lucien Vidi
2. John Venn
3. Theophilus Van Kannel
4. Lewis Urry
Option “1” is correct. Barograph was invented in 1844 by the Frenchman Lucien Vidi (1805–1866).
144. Which of the following physical quantities is a scalar quantity?
1. Weight
2. Impulse
3. Power
4. Acceleration
Option “3” is correct. Power is the ratio of two scalar quatities, and is thus scalar quatities.
145. The unit of which physical quantity is not pascal?
1. Moment of inertia
2. Pressure
3. Stress
4. Young’s modulus
Option “1” is correct. Pascal is not unit of Moment of Inertia. Moment of inertia may be expressed in units of kilogram metre squared (kg. m2) in SI units.
146. Atmospheric pressure is measured by __________.
Option “1” is correct. Atmospheric pressure is measured by Barometer.
147. Electric motors operating at low voltages tend to burn out because-
1. They draw more current which is inversely proportional to the voltage.
2. They draw more current which is inversely proportional to the square root of the voltage.
3. They draw heat proportional to V2.
4. Low voltage sets in electrical discharge.
Option “1” is correct. Electric motors operating at low voltage tend to burn out because they draw more current which is inversely proportional to the voltage.
148. What is the SI unit of atmospheric pressure?
1. Pascal
2. Knot
3. Joule
4. Ohm
Option “1” is correct. The Pascal is SI unit of pressure.
149. The absorption of ink by blotting paper involves-
1. Viscosity of ink
2. Capillary action phenomenon
3. Diffusion of ink through the blotting
4. Siphon action
Option “2” is correct. The absorption of ink by blotting paper involves Capillary action phenomenon.
150. Who invented Neon Lamp?
1. Vint Cerf
2. David Chaum
3. Georges Claude
4. Josephine Cochrane
Option “3” is correct. Georges Claude invented Neon Lamp.
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English