CBSE 2025 · Region 1 · Set 2 · Q17 · 2 marks
Show that $\displaystyle \overrightarrow{\mathrm{E}}=\rho \overrightarrow{\mathrm{j}}$ leads to Ohm's law. Write a condition in which the Ohm's law is not valid for a material.
Marking-scheme solution
$\displaystyle \vec{E}=\rho \vec{j}$
$\displaystyle \frac{V}{l}=\rho \frac{I}{A}$
$\displaystyle \frac{V}{I}=\rho \frac{l}{A}=$ constant (Ohm's Law)
Condition for non-validity of Ohm's Law:
High temperature / in semiconductor
Current ElectricityDrift of Electrons and the Origin of ResistivityApplyvery_short_answermedium
More from Current Electricity
- A steady current flows through a metallic wire whose area of cross-section increases continuously from one…2023 · asked 3×
- (i) Define mobility of electrons. Give its SI units. (ii) A steady current flows through a wire AB, as shown…2023 · asked 3×
- What is the order of magnitude of drift velocity of electrons in a conductor? Deduce the relation between the…2026 · asked 3×
- A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a…2026 · asked 3×
- What is meant by 'relaxation time' of free electrons in a conductor? Show that the resistance of a conductor…2024 · asked 3×
- Two batteries of emf's 3 V \& 6 V and internal resistances 0.2 Ω & 0.4 Ω are connected in parallel. This…2025 · asked 3×
- Four resistors, each of resistance R and a key K are connected as shown in the figure. The equivalent…2025 · asked 3×
- An electric iron rated 2‧2 kW, 220V is operated at 110 V supply. Find: (i) its resistance, and (ii) heat…2026 · asked 3×
CBSE Class 12 Physics past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.