Question

State and verify the law of parallel combination of resistances using three resistors.​

Answer 1

Answer:

Resistors are said to be in a parallel state when both the terminals of the resistors are connected to each terminal of the other resistors. The resistors in parallel have a common voltage across all the resistors. Here, we will use four resistors connected in parallel to find the law of combination of residents

This means that the combined resistance in the parallel circuit will be equal to the sum of the reciprocal of all the individual resistances.Therefore, the law of combination of resistances in parallel states that the reciprocal of the combined resistance of all the resistors connected in parallel is equal to the sum of the reciprocal of all the individual resistance.

Answer 2

Consider two resistances r1 and r2 are connected in series.

The series combination resistance RS is given by RS = r1 + r2

When connected in parallel, the resistance of the combination is given by Rp

resistance of the combination Rp

Resistance connected in Parallel

resistance connected in parallel

Resistances r1 and r2 connected in parallel to one arm of a metre bridge

Resistances r1 and r2 connected in parallel to one arm of a metre bridge

Procedure

Set up the circuit as shown in the figure above.

Connect R1 and R2 as shown in the figure.

Tighten all plugs in the resistance box by pressing and rotating each plug to assure that all plugs make good electrical connections. Using sandpaper clean the ends of connecting wires before making the connections.

Remove some plug(s) from the resistance box to get the suitable value of resistance R

Get a null point D on the metre bridge wire by sliding the jockey between ends A and C.

Note the value of the resistance R and lengths AD and DC.

Calculate the experimental value of the equivalent parallel resistance

Repeat the experiment for four more values of resistances R. Obtain the mean value of unknown resistance.

Observations And Calculations

sl.no Resistance R (ohm) Resistance from the resistance box R (ohm) Length AD=l Length DC=100-1 Rp=100-1/l Mean resistance (ohm)

R1 only 1.

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