1. SI unit of luminous intensity is___________?
A. lumen
B. lux
C. candela
D. watt
Ans & Exp : : C Luminous intensity is a measure of the wavelengthweighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd).
2. If a bomb dropped from an airplane explodes in mid-air _________?
A. its KE increases
B. its total energy increases
C. its total energy decreases
D. its total momentum decreases
Ans & Exp : : A The kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes.
3. Fat can be separated from milk in a cream separator because of __________?
A. cohesive force
B. gravitational force
C. centripetal force
D. centrifugal force
Ans & Exp : : D The centrifugal separator was invented in 1897. By the turn of the century it had altered the dairy industry by making centralised dairy processing possible for the first time. It also allowed removal of cream and recovery of the skim milk in a fresh state.
4. Melting point of ice ____________.
A. increases with increase of pressure
B. decreases with increase of pressure
C. is independent of pressure
D. None of these
Ans & Exp : : B
Ans & Exp : : B
5. Radioactivity was discovered by_________?
A. J.J. Thomson
B. W.Roentgen
C. H.Becquerel
D. M. Curie
Ans & Exp : : C Antoine-Henri Becquerel is known for his discovery of radioactivity, for which he received the Nobel Prize for Physics in 1903. Unstable atomic nuclei will spontaneously decompose to form nuclei with a higher stability. The decomposition process is called radioactivity.
6. If the temperature inside a room is increased, the relative humidity will______?
A. increase
B. decrease
C. remain unchanged
D. none of these
Ans & Exp : : B This is because temperatures in the home can be much different than the temperature outside. This is because of that important relationship between temperature and how much maximum moisture can be in the air.
7. In a transistor, the base is ________________.
A. an insulator
B. a conductor of low resistance
C. a conductor of high resistance
D. an extrinsic semiconductor
Ans & Exp : : D A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit.
8. Nights are cooler in the deserts than in the plains because _____________.
A. Sand radiates heat more quickly than the earth
B. The sky remain clear most of the time
B. The sky remain clear most of the time
C. Sand absorbs heat more quickly than the earth
D. Of none of the above reasons
Ans & Exp : : A Because desert air contains less moisture and because cloud cover is less frequent in deserts, temperatures vary more widely between day and night in deserts than in other areas. Deserts may experience temperature variations of 30-40 degrees between day and night (vs 2030 degrees in other areas), this means a nighttime low of 70-80 degrees after a 110 degree day
9. When we hear a sound, we can identify its source from ____________.
A. wave length of sound
B. the overtones present in the sound
C. the intensity of sound
D. the amplitude of sound
Ans & Exp : : B An overtone is any frequency higher than the fundamental frequency of a sound. Using the model of Fourier analysis, the fundamental and the overtones together are called partials. Harmonics, or more precisely, harmonic partials, are partials whose frequencies are integer multiples of the fundamental.
10. A boy is standing in front of a plane mirror at a distance of 3 m from it. What is the distance between the boy and his image?
A. 3 m
B. 6 m
C. 4.5 m
D. None of these
Ans & Exp : : B The image formed by a plane mirror is always virtual upright, and of the same shape and size as the object it is reflecting. A virtual image is a copy of an object formed at the location from which the light rays appear to come
11. Energy is continuously generated in the sun due to ________________.
A. Nuclear fusion
B. Nuclear fission
C. Radioactivity
D. Artificial radioactivity
Ans & Exp : A