anphysics1964

   A man can hear the sound of frequency 1 Hz, 1000 Hz, 200 Hz, 5 MHz, Ans.     As you know that a man can hear the sound of frequency between 20 Hz and 20,000 Hz.               Moreover, you know the sounds of frequencies less than 20 Hz i.e. sub sonic and more than 20,000                 Hz i.e. ultrasonic, man can not hear. Therefore correct option is 2. 1000 Hz.

  The image formed by a plane mirror is                                                                        Erect and diminished Erect and enlarged Inverted and of same size Erect and of same size Ans.    As we see in our dressing table mirror or in other domestic mirror, our image is always  erect                   and of same size,  therefore option  4. Erect and of same size  is correct.

  Two plane mirrors are placed making an angle of  60 ˚ in between them. For an object placed in between the mirrors, the number of images formed will be                                                                                                                                                              3 5 6 Infinite   Ans. As per above figure and as we know that n umber of images formed when two plane mirrors are kept at an angle   q   degrees is:  q 3 6 0 ​ − 1 i.e.,  6 0 3 6 0 ​ − 1 = 6 − 1 = 5 For more description click on Figure after pressing Ctrl...

   A real and enlarged image can be obtained by using  Convex mirror Plane mirror Concave mirror Convex and plane mirror                                                  Ans.     Please see above  to understand clearly that when object AB is between focal point and centre              of curvature, the image A'B' is real and enlarged.            So, it is clear that correct option is  3. Concave mirror

  Convert 1 mm Hg pressure in Pascal. (Density of Hg = 13.6 X 10^6 Kg/m^3 and g = 9.8 m/s^2) 133.28 Pa 133.80 Pa 133.12 Pa 132.98 Pa          Ans. As we know that 760 mm of Hg pressure = 101300 Pa                    1 mm of Hg pressure = 101300/760 = 133.28 Pa,                 Therefore, option  1. 133.28 Pa  is correct.

   A hydrometer is used to measure the following quantity of liquid Density Volume Relative density Pressure         Ans.  The correct option is  3. Relative density

  On Fahrenheit  scale, the boiling point of water is   100 ˚F  98.7 ˚F  212 ˚F  220 ˚F Ans. As per the given figure, boiling point of  water is 212 ˚F , therefore option  3. 212 ˚F  is correct.

   A body rises vertically up to a height of 125 m and comes back at the point of projection in 5 s. The average speed of the body was  25 m/s, 50 m/s, Zero None of these          Ans.     As we know that speed = distance traveled / time taken,                         Here, as the speed is changing  continuously,                         Average speed = total distance traveled / total time taken                                                       =  (125 m + 125 m) / 5 s,                                       ...

   In an instrument, there are 25 divisions on the vernier scale which coincide with 24th division of the main scale. 1 cm on main scale is divided in 20 equal parts. The least count of the instrument is  0.002 cm 0.05 cm 0.001 cm 0.02 cm      Ans. As we know that the least count of a vernier calipers is              = the value of smallest division of main scale / number of divisions of vernier scale                 = (1 cm / 20) / 25               = (10 mm / 20) / 25               = 0.5 mm / 25               = 0.02 mm               = 0.002 cm             Therefore, option  1 that is  0.002 cm  is correct.

   In a vernier calipers, there are 10 divisions on the vernier scale and 1 cm on the main scale is divided in 10 parts. While measuring a length, the zero of the vernier lies just ahead of 1.8 cm mark and 4th division of vernier coincides with a main scale division. The value of length is  1.804 cm 1.840 cm 1.800 cm None of these              Ans.     As we know that the measurement taken by a vernier calipers                         = reading on main scale just before zero mark of vernier scale                              + (number of divisions of vernier scale coinciding with any main scale division                                 x least count of the vernier calipers) ...

   A brick of weight 4 kgf having dimensions 20 cm x 10 cm x 5 cm exerts maximum pressure on surface when it is placed on ground with its  1.       Longest side (20 cm) vertical 2.       Shortest side (5 cm) vertical 3.       Medium side (10 cm) vertical 4.       None of these Ans.     As you know that pressure = force / area           Here, force is given i.e.4 kgf.           For pressure to be maximum, area will be minimum            Now area will be minimum when longest side is vertical.            Therefore  option 1. Longest side (20 cm) vertical is correct.