41. A body is thrown vertically upward from the ground. It reaches a maximum height of 20 m in 5 sec. After what time, it will reach the ground from its maximum height position?

40. A stone released with zero velocity from the top of a tower, reaches the ground in 4sec. The height of the tower is ( g = 10 m/s2 )

39. Three different objects of masses m1, m2 and m3 are allowed to fall from rest and from the same point O along three different frictionless paths. The speeds of the three objects on reaching the ground will be in the ratio of

38. The water drops fall at regular intervals from a tap 5 m above the ground. The third drop is leaving the tap at an instant when the first drop touches the ground. How far above the ground is the second drop at that instant? ( Take g = 10 m/s2 )

11. Which of the following, when added as an impurity, into the silicon, produces n-type semiconductor ?

67. The hypermetropia is a ?

29. An achromatic combination of lenses is formed by joining ?

28. A lens is placed between a source of light and a wall. It forms images of area $A_1$ and $A_2$ on the wall for its two different positions. The area of the source of light is ?

2. If two mirrors are kept inclined at $60^◦$ to each other and a body is placed at the middle, then total number of images formed is ?

If the potential of a capacitor having capacity 6μF is increased from 10 V to 20 V, then increase in its energy will be ?

The formation of a dipole is due to two equal and dissimilar point charges placed at a ?

An electric dipole, consisting of two opposite charges of 2 × 10−6C each separated by a distance 3 cm is placed in an electric field of 2 × 105 N/C. Torque acting on the dipole is ?

There is an electric field E in X-direction. If the work done on moving a charge of 0.2C through a distance of 2 m along a line making an angle 60◦ with x-axis is 4 J, then what is the value of E ?

A charge ’ q ’ is placed at the centre of the line joining two equal charges ’ Q ’. The system of the three charges will be in equilibrium if ’ q ’ is equal to ?

If the force on a rocket moving with a velocity of 300 m/sec is 345 N, then the rate of combustion of the fuel, is