NEETPhysicsCurrent Electricity
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Ohm's law holds only for small currents in metallic wire not for high currents. Reason (R) : For metallic wire resistance increases with increase in temperature. In the light of the above statements, choose the most appropriate answer from the options given below:
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A).
- BBoth (A) and (R) are true and (R) is NOT the correct explanation of (A).
- C(A) is true but (R) is false.
- D(A) is false but (R) is true.
Correct answer
A. Both (A) and (R) are true and (R) is the correct explanation of (A).
Step-by-step solution
- Assertion (A): Ohm's law holds only for small currents in metallic wire, not for high currents. - This is incorrect. Ohm's law, (V=I R ), holds as long as the material remains ohmic (i.e., the resistance is constant). It can hold for both small and large currents, provided the temperature and material properties remain unchanged. Large currents may cause heating, which can lead to a change in resistance, but this does not mean Ohm's law is inherently limited to small currents. - Reason (R): For metallic wire, res