Question

Derive the expression for equivalent resistance in series combination.

Answer 1

Answer:

hey!

Explanation:

Electricity. Derive an expression for the equivalent resistance of three resistances connected in series. Series combination: If a number of resistors are joined together so that the current flowing across each resistor is the same, then the resistances are said to be connected in series.

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Answer 2

Hi frnd

(i) Derive an expression for the equivalent resistance of three resistors RI, R2 and R3 connected in series.

(ii) Fuse of 3A, 5A and 10A are available. Calculate and select the fuse for operating electric iron of 1 kW power at 220 V line.


(i) Total potential difference across a combination of resistors in series is equal to the sum of potential difference across the individual resistors.

V = V1 + V2 + V3

Let I be the current in the circuit. The current through each resistor is also I. It is possible to replace the three resistors joined in series by an equivalent resistor of resistance R. Applying Ohm's law,

V = IR

On applying Ohm's law to the three resistors respectively we further have

V1 = IR1

V2 = IR2
V3 = IR3



But V = V1+ V2 + V3

IR = IR1 + IR2 + IR3

(ii) Power rating of electric iron = 1kW = 1000 W

V = 220 V

P = VI



Hence , a fuse of rating 5A can be used because it can bear the current.