Question

1. A piece of wire having resistance 4R is cut into four equal parts.(a)How does the resistance of each part compare with the original resistance?(b)If the four pieces are connected parallel, what is the effective resistance? 2.Two resistances when connected in parallel give resultant value of 2ohm.When connected in series the value becomes 9ohm. Calculate the value of individual resistances. 3.A wire whose resistance is 90 ohm is cut into 3 pieces of equal lengths which are then arranged in parallel. Calculate the resistance of the combination. 4. Two wires of equal length, one of copper and the other of manganin have the same thickness. Which one can be used for (a) electrical transmission lines (b) electrical heating devices? Why?

Answer 1

Ise concept :- R=k l/A

a)R
b)R/4
c)4.5ohm