Ампердің күші. №1 лаборатория «Ағымдағы магнит өрісін бақылау». Физика, 10 сынып, дидактикалық материал.

Ampere’s law law

• Ұзындығы 20 см болатын өткізгіш 1 суретте көрсетілгендей горизонталь орналасқан. Өткізгіштегі ток күші 1 А. Индукциясы 0,1 Тл болатын біртекті магнит өрісі өткізгішке қандай күшпен және қандай бағытта әсер етіп жатыр/0,01Н

Data needed to answer questions can be found in the Data, formulae and relationships sheet.

2 The diagram shows the magnetic field pattern for acurrent-carrying straight wire drawn by a student in her notes.List two errors made by the student.[2]

3A current-carrying conductor is placed in an external magnetic field. In each case below, use Fleming’s left-hand rule to predict the direction of the force on the conductor.

a b c

[3]

4The unit of magnetic flux density is the tesla.Show that: 1 T 1 N A⁻¹ m⁻¹[2]

5Calculate the force per centimetre length of a straight wire placed at right angles to a uniform magnetic field of magnetic flux density 0.12 T and carrying a current of 3.5 A.[3]

6A 4.0 cm long conductor carrying a current of 3.0 A is placed in a uniform magnetic field of flux density 50 mT. In each of a, b and c below, determine the size of the force acting on the conductor.[6]

a b c

7The diagram shows the rectangular loop PQRS of a simple electric motor placed in a uniform magnetic field of flux density B.

The current in the loop is I. The lengths PQ and RS are both L and lengths QR and SP are both x. Show that the torque of the couple acting on the loop for a given current and magnetic flux density is directly proportional to the area of the loop.[5]

8The diagram shows a rigid wire AB pivoted at the point A so that it is free to move in a vertical plane. The lower end of the wire dips into mercury. A uniform magnetic field of 6.0 10⁻³ T acts into the paper throughout the diagram.

aWhen the current is switched on, the wire continuously moves up out of the mercury and then falls back again. Explain this motion.[4]

bThe force on the wire due to the current may be taken to act at the midpoint of the wire. When the current is first switched on, the moment of this force about A is 3.5 10⁻⁵ N m.

Calculate:

ithe force acting on the wire[2]

iithe current in the wire.[2]

9The coil in the d.c. motor shown in question 6 has a length L 7.0 10⁻² m and widthx 3.0 10⁻² m. There are 25 turns on the coil and it is placed in a uniform magnetic field of 0.19 T. The coil carries a current of 2.8 A. The coil is free to rotate about an axis midway between PQ and RS.

aCalculate the force on the longest side of the coil.[2]

bCalculate the maximum torque (moment) exerted on the coil. [2]

cExplain why the force acting on the long side of the coil does not change as the coil rotatesbut the torque exerted on the coil varies. [2]