A ball is released from the top of a tower.The ratio of work  done be force of gravity in first,second and third  second of the motion of the ball is

The extension in a string obeying  Hook's law v is x. The speed of sound in the stretched string is v. If the extension in the string is increased to 1.5.x,the speed of sound will be

At the top of the trajectory of a projectile , the direction of its velocity and acceleration are

The number of turns in primary and secondary coils of a transformer is 50  and 200 respectively. If the current in the primary coil is 4A,then the current in the secondary coil is

Three weight w,2w and 3w are connected to identical spring  suspended from a rigid horizontal rod . The assembly of the rod and the weights fall freely . The position of the weight from the rod are such that

Two charges+ q and -q are  kept apart . Then at any point on the right  bisector of line  joining the two charges

With a standard rectangular bar magnet the time period of a vibration magnetometer is 4 s. The bar magnet is cut parallel to its length into four equal. The time period of vibration magnetometer  when one piece is used (in second) (bar magnet breadth is small) is

Statement (S) : Using  Huygen's eye-piece measurements can be taken but are not correct. Reason(R): The cross wires,scale and final image are not magnified proportionately because the image of the object  is magnified by two lenses,whereas the cross wire scale is magnified by one lens only.  Indentify the  correct one of the following

The refractive index of a material of a planoconcave lens is 5/3,the radius of curvature is 0.3 m. The focal length of the lens in air is

An achromatic combination of lenses produces.