MULTIPLE CHOICE QUESTIONS AND ANSWERS : SET – 2
1. The electric current density is :
   (a) a vector quantity
   (b) a scalar quantity
   (c) both
   (d) None
Ans: (a)
2. The surface of a lake is frozen in severe winter, but the water at its bottom is
   still liquid. What is the reason? [CSAT (Pre) 2011]
   (a) ice is a bad conductor of heat
   (b) since the surface of the lake is at the same temperature as the air, no heat
       is lost
   (c) the density of water is maximum at 4°C.
   (d) none of the statements (a), (b) and (c) given above are correct.
Ans: (c)
3. Lumen is the unit of : [RRB ASM/GG 2004]
   (a) Luminous intensity
   (b) Luminous flux
   (c) Both
   (d) None
Ans: (b)
4. Candela is the unit of : [RRB ASM/CC 2004]
   (a) Luminous flux
   (b) Luminous effect
   (c) Luminous pressure
   (d) Luminous intensity
Ans: (d)
5. Which one of the following pair doesn"t have the same dimension? [RRB TC
   2002]
   (a) force and pressure
   (b) work and energy
   (c) impulse and momentum
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