Closely wound solenoid \(80~\text{cm}\) long has \(5\) layers of windings of \(400\) turns each. The diameter of the solenoid is \(1.8~\text{cm}.\) If the current carried is \(8.0~\text A,\) the magnitude of \(B\) inside the solenoid near its centre is:
1. \(3.7 \times 10^{-2}~\text T\)
2. \(3.1 \times 10^{-2}~\text T\)
3. \(2.5 \times 10^{-2}~\text T\)
4. \(1.44 \times 10^{-2}~\text T\)

Two long and parallel straight wires \(A\) and \(B\) carrying currents of \(8.0~\text{A}\) and \(5.0~\text{A}\) in the same direction are separated by a distance of \(4.0~\text{cm}.\) The force on a \(10\) cm section of wire A is:

A \(3.0 ~\text{cm}\) wire carrying a current of \(10 ~\text A\) is placed inside a solenoid perpendicular to its axis. The magnetic field inside the solenoid is given to be \(0.27 ~\text T.\) What is the magnetic force on the wire?
1. \(8.1 \times 10^{-2} ~\text N\)
2. \(9.8 \times 10^{-2}~\text N\)
3. \(7.6 \times 10^{-2}~\text N\)
4. \(6.8 \times 10^{-2}~\text N\)

What is the magnitude of magnetic force per unit length on a wire carrying a current of \(8~\text{A}\) and making an angle of \(30^{\circ}\) with the direction of a uniform magnetic field of \(0.15~\text{T}?\)

A horizontal overhead power line carries a current of \(90\) A in the east to west direction. What is the magnitude and direction of the magnetic field due to the current \(1.5~\text{m}\) below the line?

A long straight wire in the horizontal plane carries a current of 50 A in the north to south direction. The magnitude and direction of the magnetic field at a point 2.5 m east of the wire is:
1. \(4 \times 10^{-6}~ T\) vertically upward
2. \(4 \times 10^{-6} ~T\) vertically downward
3. \(3 \times 10^{-6} ~T\) vertically upward
4. \(3 \times 10^{-6} ~T\) vertically downward

A long straight wire carries a current of \(35~\text{A}.\) The magnitude of the magnetic field at a point \(20~\text{cm}\) from the wire is:
1. \(3.5 \times 10^{-6} ~\text T\)
2. \(3.5 \times 10^{-5} ~\text T\)
3. \(4.5 \times 10^{-6} ~\text T\)
4. \(4.5 \times 10^{-5} ~\text T\)

A straight horizontal conducting rod of length \(0.45~\text m\) and mass \(60 ~\text {gm}\) is suspended by two vertical wires at its ends. A current of \(5.0 ~\text A\) is set up in the rod through the wires. What magnetic field should be set up normally to the conductor in order that the tension in the wires is zero?
1. \(0.13 ~\text T\)
2. \(0.06 ~\text T\)
3. \(0.26 ~\text T\)
4. \(0.18 ~\text T\)

The wires that connect the battery of an automobile to its starting motor carry a current of \(300~\text{A}\) (for a short time). What is the force per unit length between the wires if they are \(70~\text{cm}\) long and \(1.5~\text{cm}\) apart?
1. \(2.2~\text{N/m}\)
2. \(4.7~\text{N/m}\)
3. \(3.2~\text{N/m}\)
4. \(1.2~\text{N/m}\)

A uniform magnetic field of 1.5 T exists in a cylindrical region of a radius of 10.0 cm, its direction parallel to its axis along east to west. A wire carrying a current of 7.0 A in the north to south direction passes through this region. What is the magnitude and direction of the force on the wire if the wire intersects the axis?

1. 3.4 N vertically upward direction.
2. 2.1 N vertically upward direction.
3. 3.4 N vertically downward direction.
4. 2.1 N vertically downward direction.