Charges & Magnetism Test

Result

Charges & Magnetism Test - 2

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Question 1
1 / -0

A steady electric current is flowing through a cylindrical conductor.Then select the correct statement.
1. The electric field in the vicinity of the conductor is zero.
2. The magnetic field in the vicinity of the conductor is zero.
3. The electric field at the axis of the conductor is zero.
4. The magnetic field at the axis of the conductor is zero.

A
1) and 3) only

B
2) and 3) only

C
1) and 2) only

D
1) and 4) only

Solution

If a current passes through any conductor, net charge through any section is zero. hence, electric field in the vicinity of the conductor is zero. We can observe using Biot and Savart law that the magnetic field at the axis of the cylindrical wire will be zero. Electric field at the axis of the wire cannot be zero otherwise the current through the wire cannot flow.
So statement 1 and 4 are correct.
Question 2
1 / -0

A current I ampere flows along an infinitely long straight thin-walled tube, then the magnetic induction at any point inside the tube is

A
μ₀ 2I/4π

B
2I/r

C
Infinity

D
zero

Solution

Changes(if required):
Solution:
Sinθ=0 on any pt. on the axis of conductor carrying current
B=(μ_o/4Π)i(dlSinθ/r²)
Question 3
1 / -0

If a long hollow copper pipe carries a direct current, the magnetic field associated with the current will be

A
only outside the pipe

B
only inside the pipe

C
neither outside nor inside the pipe

D
both inside and outside the pipe

Solution

For a loop inside the hollow portion of the conductor, the current enclosed is zero until the loop is on the surface or inside the material of the conductor.
∴B_inside=0
For any loop outside, current enclosed by the amperian loop is not zero, hence the magnetic field is non-zero.
Question 4
1 / -0

Ampere’s circuital law is analogous to a law in electrostatics.That law is

A
Gauss’s law

B
Kirchhoff’s law

C
Faraday’s law

D
Coulomb’s law

Solution

Ampere's law is similar to Gauss's law in electrostatics.
Gauss's law correlates the surface integral of electric field E with charge q over a surface.
Ampere's law co-relates the line integral of magnetic field B with current over a closed path.
Question 5
1 / -0

In the figure shown, what is? The magnitude of current is the same in all three wires.

A
2I

B
–I

C
I

D
Zero

Solution

According to ampere law for closed loop.as the net current in the loop is zero therefore answer is zero
Let upward direction of the current be positive in sign
therefore that for downward direction will negative
B.dl=u × current inside the loop
=u×(+I-I)
=0