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Question:- What is the symbol of luminous intensity?
Answer:- Luminous intensity typically is represented by the symbol Iν, where the subscript ν denotes a photometric quantity, and its unit is the candela, an SI base unit (1 cd = 1 lumen/steradian, where the steradian is a measure of solid angle).
Question:- Which unit is lumen?
Answer:- The lumen (symbolized lm) is the International Unit of luminous flux. It is defined in terms of candela steradians (cd multiplied by sr). One lumen is the amount of light emitted in a solid angle of 1 sr, from a source that radiates to an equal extent in all directions, and whose intensity is 1 cd.
Question:- How do you convert candela to lux?
Answer:- A candela steradian per square meter (cd·sr·m⁻²) is the derived SI unit of illuminance and luminous emittance, measuring luminous flux per unit area and equal to 1 lux. One lux is equal to one lumen per square meter: 1 lx = 1 lm/m² = 1 cd·sr·m⁻².
Question:- On a rainy day, small oil films on water show brilliant colours. This is due to A. dispersion B. interference C. diffraction D. polarization
Answer:- Option B
Question:- Point A is at a lower electrical potential than point B. An electron between them on the line joining them will A. move towards A B. move towards B C. move at right angles to the line joining A and B D. remain at rest
Answer:- Option B
Question:- Materials for rain-proof coats and tents owe their water-proof properties to A. surface tension B. viscosity C. specific gravity D. elasticity
Answer:- Option A
Question:- RADAR is used for A. locating submerged submarines B. receiving a signals in a radio receiver C. locating geostationary satellites D. detecting and locating the position of objects such as aeroplanes
Answer:- Option D
Question:- Sound of frequency below 20 Hz is called A. audio sounds B. infrasonic C. ultrasonic D. supersonics
Answer:- Option B
Question:- On a clean glass plate a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because A. mercury is a metal B. density of mercury is greater than that of water C. cohesion of mercury is greater than its adhesion with glass D. cohesion of water is greater than its adhesion with glass
Answer:- Option C
Question:- Suitable impurities are added to a semiconductor depending on its use. This is done in order to A. increase its life B. enable it to withstand higher voltages C. increase its electrical conductivity D. increase its electrical resistivity
Answer:- Option C
Question:- It takes much longer to cook food in the hills than in the plains, because A. in the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100oC causing an increase in cooking time B. due to low atmospheric pressure on the hills, the water boils at a temperature higher than 100oC and therefore water takes longer to boil C. in the hills the atmospheric density is low and therefore a lot of heat is lost to the atmosphere D. in the hills the humidity is high and therefore a lot of heat is absorbed by the atmosphere leaving very little heat for cooking
Answer:- Option A
Question:- Moment of inertia is A. vector B. scalar C. phasor D. tensor
Answer:- Option D
Question:- Inside an aeroplane, flying at a high altitude, A. the pressure is the same as that outside B. normal atmospheric pressure is maintained by the use of air pumps C. the pressure inside is less than the pressure outside D. normal humidity and partial vacuum are maintained
Answer:- Option B
Question:- Sound travels with a different speed in media. In what order does the velocity of sound increase in these media? A. Water, iron and air B. Iron, air and water C. Air, water and iron D. Iron, water and air
Answer:- Option C