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Directions: Study the following question carefully and choose the right answer.
» Explain it
C
Weight of a body depends on the force of gravity acting upon it. In a lift stationary or moving with uniform speed (not with acceleration) the apparent weight of body is equal to its true weight. Because here the weight will be calculated as.

m{g-(a)}, where m is the mass of body g is the acceleration produced due to force of gravity which is 9.8m/sand a would be the acceleration due to the movement of lift. With uniform speed movement, the acceleration due to lift would be 0 here.

Hence , option C is correct.
 
2
What is the S.I. unit of pressure?
» Explain it
A
Pressure is defined as force acting on unit area of the surface.

Pressure (P) = Normal force on surface (F)/ Area of the surface (A)

Hence the S.I. unit of pressure is N/m2 also called Pascal.

Hence, option A is correct.
 
3
What is the range of wavelength of electromagnetic spectrum between which light lies?
» Explain it
C
Light is a form of energy which is propagated as electromagnetic waves. In the spectrum of electromagnetic waves it lies between ultra-violet and infra-red region and has wavelength between 3900 A° to 7800 A°.
 
Hence, option C is correct.
 
4
The force of attraction or repulsion between two point charges at rest is directly proportional to the product of magnitude of the charges and inversely proportional to the square of the distance between them. Which of the following law implies the statement presented here?
» Explain it
D
Charge is the basic property associated with matter due to which it produces and experiences electrical and magnetic effects .Coulomb’s Law is an important concept in static electricity. According to it , the force of attraction or repulsion between two point charges at rest is directly proportional to the product of magnitude of the charges and inversely proportional to the square of the distance between them.  Also this force acts on the line joining the two charges.

Hence, option D is correct.
 
5
Which of the following force holds protons and neutrons inside the nucleus of an atom?
» Explain it
C
The known forces of nature can be divided into four- gravity, electromagnetism, weak nuclear force and strong nuclear force. It is the strong nuclear force which holds protons and neutrons together inside an atom. Whereas weak nuclear force is responsible for the existence and structure of nuclei including radioactivity and nuclear fusion.

Hence, option C is correct.