If the intensity is increased by a factor of 20; then how many decibels in the sound level increased?

1. 18

2. 13

3. 9

4. 7

On the same path, the source and observer are moving such a ways that the distance between these two increases with the time. The speeds of source and observer are same and equal to  with respect to the ground while no wind is blowing. The apparent frequency received by observer is 1950 Hz then the original frequency must be (the speed of sound in present medium is 340 m/s)

1. 2068 Hz

2. 2100 Hz

3. 1903 Hz

4. 602 Hz

Consider the ray diagram for the refraction given below. The maximum value of angle θ for which the light suffers total internal reflection at the vertical surface, is 

1. ${\cos }^{-1}\left(\frac{3}{4}\right)$

2. ${\sin }^{-1}\left(\frac{3}{4}\right)$

3. ${\tan }^{-1}\left(\frac{4}{3}\right)$

4. ${\cos }^{-1}\left(\frac{4}{3}\right)$

The near point and far point of a person are 40 cm and 250 cm respectively. Determine the power of the lens he/she should use while reading a book kept at distance 25 cm from the eye.

1. 2.5 D

2. 5.0 D

3. 1.5 D

4. 3.5 D

The dimensional formula for electric flux is

1. [ ML³ I^-1 T^-3 ]

2. [ M² L² I^-1 T^-2 ]

3. [ ML³ I¹ T^-3 ]

4. [ ML^-3 I^-1 T^-3 ]

An electron of mass , initially at rest, moves through a certain distance in a uniform electric field in time . A proton of mass also initially at rest, takes time  to move through an equal distance in this uniform electric field. Neglecting the effect of gravity, the ratio , is nearly equal to

1. 1

2. $\sqrt{\frac{M_p}{M_e}}$

3 $\sqrt{\frac{M_e}{M_p}}$

4. 1836