Radio carrier waves are generated by causing electrons to oscillate rapidly in
A concave lens of focal length 20cm form an image 1/2 the size of the object. The object distance is
The diagram shows lens arrangement in
In a given circuit, the cell P has an emf 1.5V and an unknown internal resistance while cell Q has an emf 2.0V and an internal resistance of 1 ohm if the ammeter reads 50m A, Then r is equal to
