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- 1. Multiple Choice
When the coil is part of a d.c. motor, what must be connected directly to X and Y?d.c. supplyslip ringssoft-iron coresplit-ring commutator - 2. Multiple ChoiceThe diagram shows three pairs of parallel wires with the currents in the directions shown.
Which forces do the pairs of wires experience?
X, Y, Zattraction, none, repulsionattraction, repulsion, attractionnone, attraction, nonerepulsion, attraction, repulsion - 3. Multiple ChoiceEach of the diagrams below is a cross-section through two parallel current-carrying conductors.
Which diagram correctly shows the magnetic field pattern formed by the currents in the two conductors?ABCD - 4. Multiple ChoiceA wire hangs between the poles of a magnet.
When there is a current in the wire, in which direction does the wire move?ABCD - 5. Multiple ChoiceWhat is the part of a simple d.c. motor that reverses the direction of current through the coil every half-cycle?The armatureThe brushesThe commutatorThe slip rings
- 6. Multiple ChoiceThe diagram shows a beam of electrons entering a magnetic field.
What is the effect of the magnetic field on the electrons?They are deflected into the plane of the diagram.They are deflected out of the plane of the diagram.They are deflected towards the bottom of the diagram.They are deflected towards the top of the diagram. - 7. Multiple ChoiceAn alternating current is passed through a wire stretched between the poles of a magnet.
Which way will the wire move?left and rightright onlyup and downup only - 8. Multiple ChoiceX and Y are wires carrying electric currents at right angles to the page. P, Q and R are plotting compasses. Any effect of the Earth’s magnetic field has been ignored.
What is true about the direction and size of the currents?ABCD - 9. Multiple ChoiceThe diagram shows a beam of electrons entering a magnetic field. The direction of the field is into the page.
What will be the initial direction of the deflection of the electrons as the beam passes through the field?into the pageout of the pagetowards the bottom of the pagetowards the top of the page - 10. Multiple ChoiceThe diagram shows a two-pole single-coil electric motor.
The split-ring commutator reverses the current in the coil as it rotates.How many times is the current reversed if the coil is rotated once?1234 - 11. Multiple ChoiceWhich of the following has no effect on the size of the turning effect on the coil of an electric motor?the size of the current in the coilthe direction of the current in the coilthe number of turns in the coilthe strength of the magnetic field
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