Help for my project

Im a total newbie and dont know anything about electronics.

In my project,i have hardware block which i plan to implement using,

1.arduino r3
2.4 channel 5v relay
3.Active high trigger buzzer 3.3v-5v
4.obstruction detector ir sensor 5v
5.rs232 hc05 bluetooth for communication 5v
6.Lm35 temperature sensor 5v

My question is that can i power all devices from arduino by connecting all vcc to ardinos vcc and all GND to arduinos GND.?

if i need a external power,what voltage/amp it need to have?

If you power your Arduino with 7-9V 1A through the power jack you should be fine. If you use USB power (500 mA) you may get close to the limit. I'd worry most about the relays. How much current do they draw when activated?

i had tried to measure current drawn using multimeter but multimeter is not showing any current,im connecting multimeter black to com,red to 200ma.

And then connecting vcc on arduino using red wire of multimeter and connecting black to vcc of relay.
Is it the right way? i think im connecting it in series.

But no current measurement is shaown in multimeter.Can u pls help me with this problem.?

akshaygeorge:
i had tried to measure current drawn using multimeter but multimeter is not showing any current,im connecting multimeter black to com,red to 200ma.

You need to draw a pencil diagram of the connections and post a photo of the drawing. It is too easy to misunderstand a verbal wiring description.

For current measurement the circuit should be like this

+ve ----- multimeter ---- relay coil ---- GND

...R