Chapter 11

NCERT
Class 10
Science
Solutions
1. A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R’, then the ratio R/R’ is : (a) 1/25 (b) 1/5 (c) 5 (d) 25

Question:

A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R’, then the ratio R/R’ is :

(a) 1/25             (b) 1/5

(c) 5                  (d) 25

Answer:

(d) 25

Explanation : For parallel combination of five pieces:

1/R' = 5/R + 5/R + 5/R + 5/R + 5/R

1/R' = 25/R

R'/R = 25/1

R'/R = 25

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