When the coil is part of a d.c. motor, what must be connected directly to X and Y?

• d.c. supply
• slip rings
• soft-iron core
• split-ring commutator

Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-5

The diagram shows three pairs of parallel wires with the currents in the directions shown.
Which forces do the pairs of wires experience?
X, Y, Z

• attraction, none, repulsion
• attraction, repulsion, attraction
• none, attraction, none
• repulsion, attraction, repulsion

Each 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?

• A
• B
• C
• D

A wire hangs between the poles of a magnet.
When there is a current in the wire, in which direction does the wire move?

• A
• B
• C
• D

What is the part of a simple d.c. motor that reverses the direction of current through the coil every half-cycle?

• The armature
• The brushes
• The commutator
• The slip rings

The 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. 

An alternating current is passed through a wire stretched between the poles of a magnet. 
Which way will the wire move? 

• left and right 
•  right only 
• up and down 
•  up only 

X 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? 

• A
• B
• C
• D

The 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 page
  
• out of the page
  
• towards the bottom of the page
  
• towards the top of the page
  

The 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?

• 1
• 2
• 3
• 4

Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-5