# (Electricity) How do I find the current for L1(lamp 1)? And the voltage for R1 and the resistance for R1

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llltkl | College Teacher | (Level 3) Valedictorian

Posted on

I'm Sorry! The power of the light bulb L_1 is given, which is 0.5 W.

Corrigendum:

Watt = Volt × Current

0.5 = 6 × i

`rArr` i = 0.5/6 = 0.083 Amperes(approx).

Therefore, the current through the bulb is 0.083 amperes.

llltkl | College Teacher | (Level 3) Valedictorian

Posted on

Ask one question at a time. As per the prevailing rules I am to answer only one question at a time.

E.M.F. of the circuit = 9 Volts.

In order to find the total effective resistance of the circuit, the internal resistance of the light bulb has to be worked out first.

For the light bulb `L_1` , ∆V = 6V, I = 0.5A, therefore, R = ∆V/I = 6/0.5 = 12 ohms.

Total effective resistance of the circuit = (`R_1` +12) ohms (ignoring the internal resistance of the 9V cell).

Therefore, current passing through the light bulb `L_1` (and also through the resistor `R_1` )

= `9/(R_1+12)` Amperes.