A copper wire has a diameter of 0 . 5 mm and a resistivity of 1 . 6 × 10 - 6 ohm - cm . How much of this wire would be necessary to make a resistance of 10 ohm ?

Given, Resistivity, ρ = 1 .6 × 10 − 6 Ω cm Diameter, d = 0 . 5 mm Radius, r = d 2 = 0 . 5 2 = 0 . 25 × 10 - 1 c m Resistance, R = 10 Ω The equation for resistance is, R = ρ l A R = ρ l A = ρ l π r 2 ∴ l = R π r 2 ρ = 10 × 3 . 14 × 0 . 25 × 10 - 1 × 0 . 25 × 10 - 1 1 . 6 × 10 - 6 = 12 , 265 . 62 mm

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IMPORTANT

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Two cells of voltage $10 V$ and $2 V$ and Internal resistances $10 Ω, 5 Ω$ . respectively, are connected In parallel with the positive end of $10 V$ battery connected to negative pole of $2 V$ battery (Figure). Find the effective voltage and effective resistance of the combination.

Important Questions on Current Electricity

EASY

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 3 - Current Electricity>Exercise>Q 11

Write down the mathematical expression of Kirchhoff's junction law?

MEDIUM

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 3 - Current Electricity>Exercise>Q 12

Plot a graph between the variation of current density

(j)

versus the electric field

(E)

for two conductors of different material. What information from this graph regarding the properties of conducting material, can be obtained which can be used to select suitable material foe use in making (i) standard resistance

EASY

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 3 - Current Electricity>Exercise>Q 13

A copper wire has a diameter of

0.5 mm

and a resistivity of

1.6 \times 10^{- 6} ohm

cm

. How much of this wire would be necessary to make a resistance of

10 ohm

EASY

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 3 - Current Electricity>Exercise>Q 14

Is Ohm’s law universally applicable for all conducting elements? If not, give examples of elements which do not obey Ohm’s law.

HARD

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 3 - Current Electricity>Exercise>Q 15

A few storage cells in series are to be charged from a

200 V

D.C. supply. The emf of each cell is

2.5 V

and internal resistance

0.1 Ω

. The charging current is

8 A

. In this arrangement, how many cells can be changed and what extra resistance is required to be connected in the circuit?

EASY

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 3 - Current Electricity>Exercise>Q 17

The sequence of bands marked on carbon resistors are as follows. Find, in each case, the value of the resistance with tolerance.

Green, Red, Orange.

EASY

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 3 - Current Electricity>Exercise>Q 18

The storage battery of a car has an emf of

12 V

. If the internal resistance of the battery is

0.4 Ω

, what is the maximum current that can be drawn from the battery?

MEDIUM

12th Karnataka Board

IMPORTANT

Physics Crash Course (Based on Revised Syllabus-2023)>Chapter 3 - Solved Physics Paper-2>Exercise>Q 37

What is Wheatstone bridge, derive its balanced condition for balance using Kirchhoff's law.

Two cells of voltage 10 V and 2V and Internal resistances 10 Ω ,5 Ω. respectively, are connected In parallel with the positive end of 10Vbattery connected to negative pole of 2V battery (Figure). Find the effective voltage and effective resistance of the combination.

Important Questions on Current Electricity

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Two cells of voltage $10 V$ and $2 V$ and Internal resistances $10 Ω, 5 Ω$ . respectively, are connected In parallel with the positive end of $10 V$ battery connected to negative pole of $2 V$ battery (Figure). Find the effective voltage and effective resistance of the combination.