Physics help...pls...?

Question

1. On the base of a bulb is written: 3V, 0.15 A. What does this mean? What will happen if this bulb is connected to a 1.5 V cell? What will happen if it is connected to a 4.5 V batterry?

2. The current through an electric flat iron connected to a 220V line is 4A. What is the power input of the flat iron?

3. A lamp is rated 40W and 220V. How much current will the lamp draw from the main line?

Answer 1

This is not a physics question it is an electrical question.

3v = 3 volts and .15A = .15 amps

This is the voltage and current the bulb draws.  A 1.5v cell will probably make it burn dimly, about half power. A 4.5v battery will make it burn brightly or possibly burn out. Play with this all you want as you won't get hurt experimenting with a 4.5v battery but do NOT do that with household AC electrical current!

Use search engines to find the amps to watts to volts calculations and this will solve all your questions. It's something like Amps divided by Watts equals Volts.  You look.  

Answer 2

Power (watts)=Voltage (volts) * current (amps)