EASY

Earn 100

A copper wire of length $10 m$ and radius ( $\frac{10^{- 2}}{\sqrt{π}} m$ ) has electrical resistance of $10 Ω$ . The current density in the wire for an electric field strength of $10 V m^{- 1}$ is:

Important Questions on Current Electricity

EASY

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

The current density in a cylindrical wire of radius

r = 4.0 mm

1.0 \times 10^{6} A^{2} m^{2}

. The current through the outer portion of the wire between radial distances

\frac{r}{2}

and

r

x π A

; where

x

EASY

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

Define current density. Write an expression which connects current density with drift speed.

EASY

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

The current density in a cylindrical wire of radius

4 mm

4 \times 10^{6} A m^{- 2}

. The current through the outer portion of the wire between radial distances

\frac{R}{2}

and

R

is _____

π A

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

Ohm's law is applicable to

EASY

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

The current in a conductor varies with time

t

I = 2 t + 3 t^{2}

, where

I

is in ampere and

t

in seconds. Electric charge flowing through a section of the conductor during

t = 2 \sec

t = 3 \sec

HARD

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

When

5 V

potential difference is applied across a wire of length

0.1 m

, the drift speed of electrons is

2.5 \times 10^{- 4} m s^{- 1}

. If the electron density in the wire is

8 \times 10^{28} m^{- 3}

, the resistivity of the material is close to:

EASY

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

Write down the formula for the relation of current density, specific conductivity and the electric field.

EASY

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

The resistance of a wire is

R

ohm. If it is melted and stretched to

n

times its original length, its new resistance will be

EASY

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

A current through a wire depends on time as

i = α_{0} t + β t^{2}

, where

α_{0} = 20 A s^{- 1}

and

β = 8 A s^{- 2}

. Find the charge crossed through a section of the wire in

15 s .

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

A current of

5 A

is passing through a non-linear magnesium wire of cross-section

0.04 m^{2}

. At every point the direction of current density is at an angle of

60 °

with the unit vector of area of cross-section.
The magnitude of electric field at every point of the conductor is: (resistivity of magnesium

ρ = 44 \times 10^{- 8} Ωm

)

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

The resistivity of potentiometer wire is

40 \times 10^{- 8} Ω m

and its area of cross-section is

8 \times 10^{- 6} m^{2}

. If

0.2 A

current is flowing through the wire, the potential gradient of the wire is

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

A circular wire has current density

J = (2 \times 10^{10} \frac{A}{m^{2}}) r^{2}

where

r

is the radial distance, out of the wire radius is

2 mm

. The end-to-end potential applied to the wire is

50 V

. How much energy (in joule) is converted to thermal energy in

100 s

EASY

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

A copper wire with a cross-section area of

2 \times 10^{- 6} m^{2}

has a free electron density equal to

5 \times 10^{22} {cm}^{- 3} .

If this wire carries a current of

16 A

, the drift velocity of the electron is

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

Current density in a cylindrical wire of radius $R$ varies with radial distance as $β {(r + r_{0})}^{2}$ . The current through the section of the wire shown in the figure is.

Question Image

EASY

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

In the circuit shown below, a student performing Ohm's law experiment accidentally puts the voltmeter and the ammeter as shown in the circuit below; the reading in the voltmeter will be close to
Question Image

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

The number of free electrons per

100 mm

of ordinary copper wire is

2 \times 10^{21}

. Average drift speed of electrons is

0.25 mm s^{- 1}

. The current flowing is

EASY

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

A wire of resistance

12 ohms per meter

is bent to form a complete circle of radius

10 cm

. The resistance between its two diametrically opposite points,

A

and

B

as shown in the figure is

Question Image

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

The current flowing in a copper voltmeter is

1.6 A

. The number of

{C u}^{+ +}

ions deposited at the cathode per minute is

HARD

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

A steady current

I

is set up in a wire whose cross-sectional area decreases in the direction of the flow of the current. Then, as we examine the narrowing region,

EASY

Physics>Electricity and Magnetism>Current Electricity>Ohm's Law

A conductor carries a current of

300 mA

. The number of electrons passing through it in

1

minute are ___ .

A copper wire of length 10 m and radius (10-2π m) has electrical resistance of 10 Ω. The current density in the wire for an electric field strength of 10 V m-1 is:

Important Questions on Current Electricity

Learn and Prepare for any exam you want !

A copper wire of length $10 m$ and radius ( $\frac{10^{- 2}}{\sqrt{π}} m$ ) has electrical resistance of $10 Ω$ . The current density in the wire for an electric field strength of $10 V m^{- 1}$ is: