BC547 is a NPN transistor hence the collector and emitter will be left open (Reverse biased) when the base pin is held at ground and will be closed (Forward biased) when a signal is provided to base pin.
BC547 Transistor Pinout Configuration
|Current flows in through collector
|Controls the biasing of transistor
|Current Drains out through emitter
BC547 Transistor Features
Note: Complete Technical Details can be found at the BC547 datasheet given at the download menu of this page.