Physics · Kirchhoff's laws and their applications, Wheatstone bridge, Metre Bridge
Assertion (A) : In a metrebridge ; Copper wire is connected in the left gap and
Assertion (A) : In a metrebridge ; Copper wire is connected in the left gap and silicon is connected in the right gap. When the temperature of both wires increase, balancing point shifts to right. Reason (R) :Temperature coeficient of copper is (-)Ve and that of silicon is \( (+) \) Ve.
- A. Both A \& R are true and R is the correct explanation of \( A \)
- B. Both A \& R are true and R is not a correct explanation of
- C. A is true but R is false
- D. A is false but R is true
Step-by-step solution
Copper has a positive temperature coefficient (resistance increases with temperature), while silicon has a negative temperature coefficient (resistance decreases with temperature). Thus, Reason (R) is false. In the metrebridge, when temperature increases, left gap resistance (copper) increases and right gap resistance (silicon) decreases, causing the ratio R_left/R_right to increase. This shifts the balancing point to the right, so Assertion (A) is true. Hence, A is true but R is false.
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