Question

When a potential difference of 2 V is applied across the ends of a wire of 5 m length, a current of 1A is found to flow through it. Calculate: (i) the resistance per unit length of the wire (ii) the resistance of 2 m length of this wire (iii) the resistance across the ends of the wire if it is doubled on itself.

Answer 1

 (i) V = I R ----- Ohm's law






(ii) Resistance of 2 m length of the wire = 0.4 x 2


(iii) When the wire is doubled on itself:

(1) the area of cross-section is doubled. If A is the original C.S. area, now it is 2 A.

(2) The length becomes half i.e. 










 (i) V = I R ----- Ohm's law






(ii) Resistance of 2 m length of the wire = 0.4 x 2


(iii) When the wire is doubled on itself:

(1) the area of cross-section is doubled. If A is the original C.S. area, now it is 2 A.

(2) The length becomes half i.e. 











 (i) V = I R ----- Ohm's law






(ii) Resistance of 2 m length of the wire = 0.4 x 2


(iii) When the wire is doubled on itself:

(1) the area of cross-section is doubled. If A is the original C.S. area, now it is 2 A.