A body at a temperature of 728 ° C and has surface area 5 cm2, radiates 300 J of energy each minute. The emissivity is 
(given Boltzmann constant )
 

1.  e = 0.18
2.  e = 0.02
3.  e = 0.2
4.  e = 0.15

Subtopic:  Stefan-Boltzmann Law |
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Considering normal incidence of ray, the equivalent refractive index of combination of two slabs shown in figure is 
 
1.  1.8
2.  1.43
3.  2
4.  None of the above

 

Subtopic:  Refraction at Plane Surface |
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Three particles having charges in the ratio of 2 : 3 : 5 produce the same point on the photographic film in Thomson experiment. Their masses are in the ratio of
 

1.  2 : 3 : 5
2.  5 : 3 : 2
3.  15 : 10 : 6
4.  3 : 5 : 2

Subtopic:  Various Atomic Models |
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A black body emits heat at the rate of 20 W. When its temperature is 727 ° C. Another black body emits heat at the rate of 15W, when its temperature is 227 º C. Compare the area of the surface of the two bodies, if the surrounding is at NTP.
 

1.  16 : 1
2.  1 : 4
3.  12 : 1
4.  1 : 12

Subtopic:  Conduction |
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The pressure on a square plate is measured by measuring the force on the plate and the length of the sides of the plate by using the formula P=Fl2 . If the maximum errors in the measurement of force and length are 4% and 2% respectively, then the maximum error in the measurement of pressure is

 

1.  1%
2.  2%
3.  8%
4.  10%

Subtopic:  Errors |
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Four resistance   are connected so that they form the side of a rectangle AB, BC, CD and DA respectively. Another resistance of  is connected across the diagonal AC. The equivalent resistance between A and B is
 
1.  2Ω
2.  5Ω
3.  7Ω
4.  10Ω

 

Subtopic:  Combination of Resistors |
 62%
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The velocity of a particle moving in the x – y plane is given by 
 and  
Where, t = 0, x = 8 and y = 0, the path of the particle is
 
1.  A straight line
2.  an ellipse
3.  a circle
4.  a parabola

 

Subtopic:  Speed & Velocity |
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