Phenomenon of formation of three dimensional image by interference of two light beams from laser or other coherent sources of light is called _____.

1. 1. Radiography
   2. X-ray photography
   3. Optical photography
   4. Holography

Which one of the following statement is correct?

1. 1. Does not radiate heat but absorbs heat from the surrounding
   2. Does not radiate heat
   3. Radiates heat but absorbs more heat from the surrounding
   4. Radiates heat more than that absorbed by it form the surrounding

A needle smeared with vaseline when lowered slowly on the surface of water in a horizontal position appears to float. The phenomenon is an example of _____.

1. 1. Osmosis
   2. Surface tension
   3. Capillary action
   4. Archimedes principle

Rectifiers are used to convert _____.

1. 1. High voltage to low voltage
   2. Low voltage to high voltage
   3. DC to AC
   4. AC to DC

when water boils, its temperature _____.

1. 1. Begins to decrease
   2. Remains constant
   3. Begins to increase
   4. Fluctuates

During rusting _____.

1. 1. Iron gains weight
   2. Iron volatilizes
   3. Weight of iron remains unchanged
   4. Iron loses weight

Which of the following metals is used in aircraft?

1. 1. Titanium
   2. Chromium
   3. Palladium
   4. All of these

In electric fittings, the wires are earthed because _____.

1. 1. In case of a short circuit, current passes to the earth
   2. It completes the electric circuit
   3. It reduces fluctuation
   4. It avoid leakage of electricity

Sound travels with a different speed in different medial. In what order does the velocity of sound increase in these media?

1. 1. Iron, air and water
   2. Water, iron and air
   3. Air, water and iron
   4. Iron, water and air

Four identical kettles with the same amount of water, have bases made of different metals of the same thickness. If these are placed on identical flames water will boil first in the kettle with a base made of _____.

1. 1. Copper
   2. Aluminum
   3. Steel
   4. brass