General Physics
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286 Stars in the sky appear to twinkle due to :
A
a series of refractions
B
a series of reflections
C
a surface tension phenomenon
D
multiple diminishing brightness
287 ‘Hydraulic brakes’ work on the principle of :
A
Pascal’s law
B
Thomson’s law
C
Newton’s law
D
Bernoulli’s theorem
288 Stars appear twinkling because of ......... of light.
A
Reflection
B
Scattering
C
Emission
D
Absorption
289 In mirrors the back surface is coated with a thin layer of :
A
Mercury
B
Silver
C
Red oxide
D
Silver nitrate
290 Hypermetropia or longsight can be corrected by using :
A
Bifocal lenses
B
Cylindrical lenses
C
Concave lenses
D
Convex lenses
291 Parabolic mirros are used in :
A
Car headlights
B
Driving mirrors
C
Dentists mirros
D
Shaving mirros
292 A device which is used to limit the current in an electrical circuit is called a
A
Grid
B
Fuse
C
Hub
D
Conductor
293 An optically plane surface reflects a beam of light
A
as a parallel beam in one direction
B
as diffused beams in all directions
C
as parallel beams in all directions
D
as a diffused beam in one
direction
294 Red is used as an emergency or danger signal as
A
it is a striking colour
B
its wavelength is the longest
C
it is scattered
D
it has very high energy
296 Small bubbles are perfectly spherical because of :
A
Gravity
B
Pressure
C
Viscosity
D
Surface tension
297 Water is used in car radiator because of its
A
low density
B
easy availability
C
high specific heat capacity
D
low boiling point
