Ohm’s law may also be stated by the equation j ⇀ = σ E ⇀ . What do the symbols j ⇀ , σ and E ⇀ stand for? Show that the combination of units on the two sides are identical.

Formula used: ȷ → = σ E → Here, j → = Current density ( j → = I / A ) σ = Electrical conductivity E → = Electric field. S.I. unit of j = A / m 2 S.I. unit of σ = ( − Ωm ) − 1 S.I. unit of E = V / m . then values in Eq, J = σE A m 2 = ( Ωm ) - 1 V m A m 2 = V ⋅ Ω m 2 A m 2 = A m 2

E M B I B E

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 2

HARD

12th ICSE

IMPORTANT

Earn 100

Obtain an expression showing the relation between the current-density $j$ in a current-carrying conductor, the drift velocity $υ_{d}$ , the number of free electrons per unit volume $n$ and the electronic charge $e .$

Important Questions on Electric Resistance and Ohm's Law

MEDIUM

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 3

The current flowing through a conductor is given by $I = n e A v_{d} .$

Identify each term in the equation.

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 3

The current flowing through a conductor is given by

I = n e A v_{d} .

Obtain an expression for

v_{d}

, if the current flowing through the conductor of length

l

has its ends maintained at a potential difference of

V

volt.

MEDIUM

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 4

What is meant by specific resistance (resistivity) of a conductor? Write its unit. Show how the electric resistance of a wire depends on the resistivity of its material, its length and area of cross-section.

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 5

Ohm’s law may also be stated by the equation $\overset{⇀}{j} = σ \overset{⇀}{E}$ . What do the symbols $\overset{⇀}{j}$ , $σ$ and $\overset{⇀}{E}$ stand for? Show that the combination of units on the two sides are identical.

EASY

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 6

Define resistivity of a conductor. Explain the variation of resistance with temperature in metallic wire.

MEDIUM

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 6

Define resistivity of a conductor. Explain the variation of resistance with temperature in a piece of carbon.

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 7

Write down a simple relationship to show the variation of resistance with temperature. Define temperature coefficient of resistance. In what way the temperature coefficient of carbon is different from that of common conductors?

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 8

Explain energy transfer in electric circuits. Prove that the energy liberated from an electric circuit is given by