KS3 Physics revision worksheet 1 - Electricity, Magnetism, Electromagnetism
Exam Question Answers
1. (a)
1 (L4)
both poles are required for the mark
(b) (i)
1 (L4)
all four poles are required for the mark
(ii) any one from 1 (L4)
· iron
· steel accept ‘cobalt or nickel’
(c) any one from 1 (L4)
· wood or it is not magnetised accept ‘the wood does not have any poles’
· wood or it is not magnetic accept ‘wood is not a magnet’
accept ‘the magnet does not attract wood’
accept ‘magnetism cannot pass through wood’
· it increases the distance between the magnets
· the magnets are too far apart
· the magnets are weak
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2. (a) any one from 1 (L3)
· the circuit is not complete accept ‘there is no circuit’
· a wire is missing
· two of the bulbs are not connected
accept ‘the bulbs are not connected’
do not accept ‘the switch might be broken’ or ‘there is a loose connection’
(b) another cell or battery accept ‘put the bulbs in parallel’ 1 (L5)
or ‘make a parallel circuit’
or ‘use new batteries’
do not accept ‘use stronger batteries’
(c) Each bulb is the same brightness. Ö if more than one box is ticked, 1 (L4)
award nomark
(d) (i) they go out accept ‘they stop working’ 1 (L3)
do not accept ‘they get dimmer’
(ii) any one from 1 (L4)
· they stay on or stay the
same accept ‘they get brighter’
· they do not go out accept ‘only the broken bulb goes out’
· nothing
(e) a letter S drawn onto or close to the wire in the top part of the circuit 1 (L4)
anywhere between the two junctions
accept an open switch symbol drawn onto the diagram
do not accept a letter S drawn mid-way between the top two wires or at a junction between the top two wires as shown below
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3. (a) gravity accept ‘weight’ 1 (L5)
magnetic force or magnetism accept ‘repulsion’ or ‘upthrust’ 1 (L5)
answers may be in either order
do not accept ‘air resistance’
(b) (i) 12 1 (L5)
(ii) any one from 1 (L6)
· the paper cup stopped accept ‘it hit the bottom’
moving
· the paper cup reached the accept ‘the paper cup could not go any further’
bottom magnet
(c) any one from 1 (L6)
· iron is magnetic accept ‘aluminium is not magnetic’
· iron nails are attracted to a accept ‘the rivets are not attracted to a magnet’
magnet
· there is a magnetic force on the iron
do not accept ‘aluminium or rivets are less magnetic’
do not accept ‘iron or nails are more magnetic than aluminium or rivets’
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4. (L5)
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5. (a) • both picked up the same number or four paper-clips 1 (L5)
accept ‘they both picked up the same number’
accept ‘same amount of paper-clips’
accept ‘there were 5 out of 9 paper-clips left for both’
accept ‘the same mass of paper-clips’
‘they hold the same clips’ is insufficient
(b) any one from 1 (L6)
• it does not stay magnetised
• it can be turned off
accept ‘you cannot turn steel off’
• objects do not stay attached to it
• iron loses its magnetism
• steel stays magnetised
(c) (i) any one from 1 (L6)
• the greater the distance the lower the reading
• the further away the smaller the reading
accept the converse
accept ‘at big distance the field is weaker’ or the converse
accept ‘at 50 mm the reading is lower’
accept the converse
do not accept ‘the bigger the distance the smaller the amps or current’
(ii) • the greater the current the stronger the electromagnet 1 (L6)
(iii) any one from 1 (L6)
• change the number of turns
• change the thickness of the wire
• change the diameter of the core
accept ‘use more coils’
accept ‘use fewer or less coils’
accept ‘put the coils closer together’ or the converse
accept ‘change the metal of the coils’
accept ‘use a different sized core’
accept ‘use nickel or cobalt core’
accept ‘use a different core’
‘use bigger coils’ is insufficient
‘use more wire’ is insufficient
do not accept ‘add more batteries’
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6. (a) any two from: 2 (L6)
· manufacturing differences or bulbs are different
accept ‘different resistances’
accept ‘different ages’
· reading error
· dirty contacts accept ‘bulbs were not screwed in properly’
· unreliable or inaccurate meter accept ‘faulty ammeter’
accept ‘different wires’ or ‘differences in the wires’
(b) 0.75 1 (L6)
(c)
both axes must be labelled correctly with both the variable and the unit
Y axis : current, in amps or A or milliamps or mA 1 (L7)
accept ‘I , in amps’
X axis : time, in hours or minutes or seconds
accept ‘t, in hours’
a line or curve from top left to bottom right 1 (L7)
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7. (a) (i) · add more coils or turns 1 (L6)
accept ‘put coils or turns closer together’
do not accept ‘move it closer’
· increase the current 1 (L6)
accept ‘increase the number of cells or batteries’
accept ‘increase the voltage or power’
(ii) 1 (L7)
all four poles must be correct for the mark
(b) (i) any one from 1 (L7)
· steel stays magnetised
· iron loses its magnetism
· the switch would stay closed
· the switch would not spring open
(ii) · copper is a better conductor than iron 1 (L7)
accept the converse
accept ‘copper has a lower resistance’
accept ‘iron or the reed switch has a greater resistance’
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8. (a) (i) any two from 2 (L7)
· the current in the coil produces a magnetic field
accept ‘the current produces a magnetic field’ or ‘the coil produces a magnetic field’ or ‘the coil becomes an electromagnet’
· the rods are magnetised in the same direction
accept ‘the N or S poles are next to eachother’
· the rods repel each other
(ii) nothing or they stay where they are 1 (L7)
accept ‘they become demagnetised’
(b) nothing happens 1 (L7)
because only the iron rod becomes magnetised or because the brass rod 1 (L7)
doesnotbecomemagnetised
accept ‘because brass is not magnetic’
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9. (a) any one from 1
· flow in X = flow in Y + flow in Z
· x = y + z accept ‘Y + Z = X’
· rate of flow into the junction = the total rate of flow out of it
(b) (i) 70 1
70 both rates are required for the mark
(ii) charge accept ‘electrons’ 1
do not accept ‘current’
(c) any one from 1
· electricity can only flow in conductors or metal
· air is an insulator so electricity cannot flow through it
do not accept ‘there is no current because there is a break in the circuit’ or ‘the empty socket breaks the circuit’ or ‘a closed circuit is needed’
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10. (a) any one from
· the current flows in opposite directions so there is no magnetic field 1’
do not accept ‘the currents in A and B cancel out so there is no field’ or ‘the coils are wound in opposite directions
· because the two magnetic fields or forces cancel out
do not accept ‘they cancel out’
(b) there is no current in coil A accept ‘there is current in coil B only’ 1
or ‘the currents in the coils are different’ or ‘coil A will lose its magnetic field’
do not accept ‘there is current in coil B’
the magnetic fields no longer cancel accept ‘the iron core becomes magnetised’ 1
or ‘the magnetic fields are different’
the armature will be attracted or pulled towards the core 1
answers may be in any order
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Ballard School 1