Question

A 6 volt,12 watt lamp is connected in series with a resistor R and a source of 12 volt supply.What is the purpose of the resistor R.Calculate the value of the resistor R for the proper working of the lamp.What is the current flowing through the circuit.

Answer 1

Explanation:

• The maximum current that a light rated at 6 V, 12 W can handle is

         I = P÷V= 12÷6 =2A

• The resistance of a lamp's filament when it is in use:

        R.=V² ÷ P = (6)² ÷ 12=3Ω

• When a resistor R is connected in series with the bulb, the total resistance of the circuit is

        =R+R.= (R+3)Ω

• The current in the circuit should be 1 = 2 A with a voltage source of 12 V.

• Following Ohm's law,

        V = IR

        ∴12= 2(R+3)

        or

        12=2R+6

        or

        R=3Ω

• Q: What is the purpose of the resistor R.

• A resistor is a two-terminal passive electrical component that acts as a circuit element by implementing electrical resistance.
• Resistors are employed in electronic circuits for a variety of purposes, including reducing current flow, adjusting signal levels,
• dividing voltages, biassing active devices, and terminating transmission lines.