How 6 volt convert to 3 volt dc use for risestance?

Answer 1

You could use a resistor, but you would need to know what the current of the circuit is. Use the equation;

R = V/I

R - Resistance

V - Voltage

I - Current

and divide the 3 volts (difference) by the current to get an appropriate resistor size.

Answer 2

Transforming dc voltage is not as simple as transforming ac voltage. This is why most of the power we use is ac.

The simplest way to do what you ask is to wire IN SERIES 2 equal resistances. If the resistances are EQUAL and are wired IN SERIES, you will accomplish what you ask.

Answer

Two resistors, connected in series with each other, across the 6-V supply will provide you with a 'voltage divider'. With no load connected, two identical resistors will divide the 6-V equally. However, when you connect your load across one or other of these resistors, this is no longer true because what is called the 'loading effect' (the load will alter the balance of the two resistors). So the resistance of the load must be factored in when the voltage divider is designed. Any good electrical texbook will describe how to do this.

Two incandescent light bulbs, each requiring 3 volts and of equal wattage, can be wired to a 6 volt circuit IN SERIES and will work perfectly without any other calculations or design.