A speech signal given by 11 sin(2200 $$\pi$$t) V is used for amplitude modulation with a carrier signal given by 44 sin(6600 $$\pi$$t) V. The minimum amplitude of modulated wave will be :

A hydrogen atom in ground state absorbs 12.09 eV of energy. The orbital angular momentum of the electron is increased by :

A person starts his journey from centre 'O' of the park and comes back to the same position following path OPQO as shown in the figure. The radius of path taken by the person is 200 m and he takes 3 min 58 sec to complete his journey. The average speed of the person is _____________ ms^$$-$$1. (take $$\pi$$ = 3.14)

An employee of a factory moving away from his workplace by a car listens to the siren of the factory. He drives the car at the speed of 72 kmh^$$-$$1 in the direction of wind which is blowing at 72 kmh^$$-$$1 speed. Frequency of siren is 720 Hz. The employee hears an apparent frequency of ____________ Hz.

(Assume speed of sound to be 340 ms^$$-$$1)