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Asked by rasjad355 | 15 Jan, 2023, 04:49: PM
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Question (42)
 
Initial speed of block when it is placed on conveyor will be 4 m/s
 
Initial kinetic energy = (1/2) m v2 = 0.5 × 0.5 × 4 × 4 = 4 J
 
Workdone to stop the block equals initial kineteic energy
 
Workdone to stop the block = 4 J
 
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Question (43)
 
!6 gm of helium = 16/4 = 4 moles
 
Constant volume specific heat of helium (mono-atomic) = (3/2)R J/( mole K )
 
Constant pressure specific heat of helium (mono-atomic) = (5/2)R J/( mole K )
 
28 gm of nitrogen = 28/28 = 1 moles
 
Constant volume molar specific heat of nitrogen (di-atomic) = (5/2)R J/( mole K )
 
Constant pressure molar specific heat of nitrogen (di-atomic) = (7/2)R J/( mole K )


mole fraction of helium = 4/5  ; mole fraction of nitrogen = 1/5   ;
 
 
Constant volume molar specific heat of mixture =  [ (4/5) (3/2) R ] + [ (1/5) (5/2) R ] = (17/10)R
 
Constant pressure molar specific heat of mixture =  [ (4/5) (5/2) R ] + [ (1/5) (7/2) R ] = (27/10)R
 
Ratio of constant volume molar specific heat to constant pressure molar specific heat is  (17/27)
 
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question (44)
 
To get maximum current through zenar diode , let us consider maximum voltage 80V of power supply.
 
Potential difference across 5 kΩ resistance is ( 80 -30 ) V = 50 V
 
Current Is through 5 kΩ is = 50 V / 5 kΩ = 10 mA .
 
Since potential difference across zenar diode is 30V ,
 
current through 20kΩ load resistance is ( 30V / 20kΩ ) = 1.5 mA
 
Current through zenar diode = ( 10 -1.5) mA = 8.5 mA
 
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Question (45)
 
Point object is at P at a distance u = - 30 cm from convex lens of focal length f = 20 cm .
(Cartesian sign convention is followed )
 
image distance  v from lens without convex mirror is calculated using lens equation
 
begin mathsize 14px style 1 over v minus 1 over u space equals space 1 over f end style
 
begin mathsize 14px style 1 over v minus fraction numerator 1 over denominator negative 30 end fraction space equals space 1 over 20 end style
 
we get v = 60 cm from above expression.
 
Now if we place convex mirror at a distance 20 cm from convex lens as shown in figure and
if we get image at R that is side by side of object point P , then light rays are retraced in same path
of incidence after reflection by convex mirror.
 
If the convex mirror retrace the light rays in same path of incidence after reflection ,
then light rays incident on convex mirror at normal direction.
 
Hence if we extend the point of incidence towards first image point Q , Then Q is centre of curvature.
 
Hence radius of curvature of convex mirror = ( 60 - 20 ) cm = 40 cm  
Answered by Thiyagarajan K | 15 Jan, 2023, 08:42: PM
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