NEET Physics Question - Current Electricity - Variation of Resistance with Temperature

Assertion (A): If a resistor is connected to a battery, the current decreases when the temperature increases.

Reason (R): For most of the resistors, resistance increases with increase in temperature.

(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)

(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)

(3) (A) is true but (R) is false

(4) Both (A) and (R) are false

Solution:

Concept: Ohm's law, temperature dependence of resistance.
Formula: \(I = V/R\), \(R\) increases with \(T\) for most resistors.
Solution: For most metallic resistors, resistance \(R\) increases with increasing temperature \(T\). When connected to a battery (constant voltage \(V\)), the current \(I = V/R\) decreases as \(R\) increases. Thus, A and R are true and R explains A.

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