Question
Fig. 7.1 shows a horizontal conducting wire XY between two opposite magnetic poles. Wire XY forms a circuit with an ammete 
(a) Explain why the reading on the ammeter is zero when the wire XY is not moving.
(b) The wire XY is moved and there is a deflection on the ammeter that indicates there is a current in the wire from X to Y.
On Table 7.1, tick one box to indicate the direction of the movement of the wire XY and explain your answer.
Table 7.1
into page | out of page | to the left | to the right | to the bottom of the page | to the top of the page |
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explanation
(c) State what is observed on the ammeter when the wire XY is moved
(i) in the opposite direction to part (b) ……………………………………………………………………..
(ii) in the same direction as part (b) but at a greater speed …………………………………………
Answer/Explanation
Answer:
(a) no cutting of (magnetic) flux / magnetic field
(b) to the top of the page / RH box
current, motion and (magnetic) field
mutually at right angles
(magnetic) field from left to right
(c)(i) opposite current (direction) / opposite deflection (on ammeter)
(c)(ii) greater current / deflection
Question
(a) The box below contains the names of some metals.
copper gold iron lead silver steel
Circle the metals which may be attracted to a magnet.
(b) A student has 3 metal bars which all look the same. Two of the metal bars are magnets and one is not.
Explain how the student can identify the two magnets without using any other equipment.
…………………………………………………………………………………………………………………………………
(c) From the metals given in (a), state the name of the metal that can be used to make a permanent magnet.
…………………………………………………………………………………………………………………………….
(d) Fig. 10.1 shows a vertical wire passing through a horizontal piece of card.
There is a direct current (d.c.) in the wire. The current produces a magnetic field around the wire.
(i) Name a piece of equipment that can be used to investigate the magnetic field produced by the current-carrying wire.
……………………………………………………………………………………………………………………..
(ii) Fig. 10.2 shows the wire and the card viewed from above.
On Fig. 10.2, carefully draw two complete field lines produced by the current-carrying wire.
Answer/Explanation
Answer:
(a) iron clearly indicated
steel clearly indicated
(b) test to see if there is repulsion/attraction
clear indication that repulsion identifies the magnets
(c) steel
(d) (i) iron filings OR (plotting) compass
(ii) at least two complete concentric circles around wire