Question

Question 22:
How does the resistance of a wire change when :
(i) its length is tripled ?
(ii) its diameter is tripled ?
(in) its material is changed to one whose resistivity is three times ?

Lakhmir Singh Physics Class 10

Answer 1

resistance(R) is directly proportional(=) to length(l) ,
inversely proportional to area(A)
I) if length length is tripled I.e 3l
for initial R = l then what is the resistance(x) if length is 3l
then x= 3R
therefore resistance become triple time of initial
ll)R= 1/A = 1/(πr²)
2r =d ( diameter ) for initial
if diameter becomes triple
x= 1/(π(6r/2)²)
x = 1/(π/9r²)
x= 1/9(R)
I.e the resistance will decrease 9 times of initial .
lll) R = resistivity (l/A)
if resistivity becomes thrice then resistance will be 3 times of initial
hope its helps u

Answer 2

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