A photocell is illuminated by a small bright source placed 1 m away. When the same source of light is placed $\frac{1}{2}\mathrm{~m}$ away, the number of electrons emitted by photo cathode would\\
(1) decrease by a factor of 4\\
(2) increase by a factor of 4\\
(3) decrease by a factor of 2\\
(4) increase by a factor of 2