Use the bulbs used in activity 6 and connect these bulbs as shown in figure 19.

Measure the potential difference across eachbulb using a voltmeter or multi meter. Note these values in your note book. What do you notice? The potential difference at the ends of each bulb is the same. These bulbs are said to be in parallel connection. Measure electric currents flowing through each bulb using ammeters. Note these values.

Let I₁,I₂and I₃be the currents flowing through R₁, R₂ and R₃ resistors respectively.

• How much current is drawn from the battery?
• Is it equal to individual currents drawn by the resistors?

Measure the current (I) drawn from the battery using the ammeter 1. SC TELANGANA You will notice that the current drawn from the battery is equal to the sum of individual currents drawn by the bulbs.

Hence we can write

I = I₁+ I₂ + I₃...................................(1)

The schematic circuit of figure 19 is shown in figure 20.

According to the Ohm’s law,

Current through R₁ is, I₁ = V/R₁

Current through R₂ is, I₂ = V/R₂

Current through R₃ is, I₃ = V/R₃

Let R_eq be the equivalent resistance of the resistors is parallel. It is shown in figure 21.

Then we get;I=V/R_eq

Substituting the values I, I₁, I₂and I₃ in equation (1), we get

V/R_eq=V/R₁+V/R₂+V/R₃

1/R_eq=1/R₁+1/R₂+1/R₃