Test: Ohm’s law & Limitations of Ohm’s Law(12 Nov) - JEE MCQ

Materials which obeys the ohm’s law show straight line in the V-I graph. Since silver is the only ohmic material in given options, it shows straight line curve.

The slope of the graph = I / V

In case of T₂, I/V is less. Hence, V/I (=R) is more.

Value of resistance increases with increasing temperature. 

Hence, T₂ >T

1 Ohm is defined as the resistance of a conductor with a potential difference of 1 volt applied to the ends through which 1-ampere current flows.
Ohms is the SI unit of electrical resistance.
 

Ohmic conductors are those which follows ohm's Law

Constantan is an copper nickle alloy which follows ohm's law 

An electrolyte is a chemical that produces an electrically conducting solution and hence conducts electrical current.

But Electrolyte can be  Ohmic as well as non-ohmic conductor

Transistor is semi-conductor device and does not follow ohm's Law

thermionic valves  - is vacuum tube (electronic tube) , uses ion emission.

So option C Constanton s an ohmic conductor.

(A) → (p) if the temperature is not very high.
(B) → (r)
(C) → (q)

Ohm’s law V = IR is an equation of straight line. Hence I - V characteristics for ohmic conductors is also a straight line and its slope gives resistance of the conductor.

The figure is showing I-V characteristics of non-ohmic or non-linear conductors.

Mobility of charged particle

= 2.5 × 10⁶m²V⁻¹s⁻¹

Resistance of a conductor is given by R = ρ l/A,
where ρ is the specific resistance, l is the length and A is the cross-sectional area of the conductor.
Now, when l = 1 and A = 1, R = ρ. So specific resistance or resistivity of a material may be defined as the resistance of a specimen of the material having unit length and unit cross-section. Hence, specific resistance is a property of a material and it will increase with the increase of temperature, but will not vary with the dimensions (length, cross section) of the conductor.
 

Current does not depend on the area of the conductor; hence it remains a constant.
Current density is inversely a constant.
Current density is inversely proportional to area (i.e.,) J∝1/A​ electric field drift speed is also inversely proportional to area (i.e.,) E∝1/A​,V_d​∝1/A​
Hence current is constant along the conductor.