A simple pendulum having bob of mass m and length of string l has time period of T. If the mass of the bob is doubled and the length of the string is halved, then the time period of this pendulum will be

In which one of the following devices, the light energy is converted into the electrical energy?

SONAR is a device that is used to measure the distance of underwater objects by a ship. Which of the following types of waves does it use for this purpose?

Which one of the following statements about the speed of sound waves is not correct?