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Question 1

LOUD SPEAKER :Motor Effect

Answer 1

1) current flows in coil. ( producing magnetic field)
2) permanent magnet also (produces magnetic field)
3) 2 magnetic fields interact = causes force.
4) force = moves coil & cone.
5) direction of force = left hand rule.
6) AC causes force & movement to alternate (swap
direction)
7) alternating movement = vibration that moves our particles =make sound.
(INSERT DIAGRAM)

Question 2

TRANSFORMER: HOW #1

Answer 2

how? = alternating current flows in primary coil

1) current causes magnetic field in cone = becomes magnetised.
2) field changes in secondary coil ( changing induced voltage in secondary coil).
3) if circuit is complete = alternating current flows

Question 3

TRANSFORMER = why soft iron core #2

Answer 3

WHY = so it can be magnetised/ do magnetised easily.

magnetism can be induced but not magnets

Question 4

TRANSFORMER = AC #3 (alternating current)

Answer 4

AC? = used so we can have a changing magnetic field (without magnetic field)= NO induced voltage
= NO current
( = because we have to cut the
field lines)

Question 5

TRANSFORMERS = step up/down #4

Answer 5

Step up = less turns on primary coil, more turns on secondary (increases voltage)
e.g national grid power lines
step down = more turns on primary
less turns on secondary (decreases voltage).
e.g phone/laptop charger.

Question 6

TRANSFORMERS = National grid #5

Answer 6

Why important =
1) less (electricity/voltage?)
IS LOST
2) too dangerous to use at home

Question 7

TRANSFORMERS = EQUATION #6

Answer 7

Vp/Vs = Np/Ns V=voltage

N= no. of turns

Question 8

POWER & EFFICIENCY #7

Answer 8

Electrical power = voltage x current
(amount of power transferred in 1 sec.)(V I)
VpIp = VsIs ( e.g 10V 3A = 30w= 5V 6A)
efficiency = USEFUL POWER OUTPUT (secondary)/
TOTAL POWER INPUT (in primary)
total=200J
useful=180J
= 180/200
= 0.9
=90%

Question 9

TRANSFORMERS = how step up/down makes transmission of electrical power make efficient.

Answer 9

1) step up = increases voltage =
2) REDUCES current
3) current linked to heating
4) = less (energy/power) lost (in transmission)
5) P= V I
6) e.g of efficiency enhancing cable detail
= good conductor, low resistance, large diameter.
7) e.g of efficiency enhancing TRANSFORMER CONSTRUCTION = low resistance coils, soft iron cone detail.

Question 10

HANGING WIRE EXPERIMENT- motor effect.

Answer 10

1) connect hanging wire to power supply (wires)
2)hang wire on clamps on clamp stand
3) wire must hang between N&S (in magnetic field)
4) put (12) volts into wire (so there’s a MAGNETIC FIELD around wire) , momentarily so there is no spark
5) force is caused from MAGNETIC FIELD.
6) force = wire has bigger bounce, until electricity supply is turned off = MOTOR EFFECT!
7) increase voltage/strength of magnet = cause bigger movement in wire. VOLTS increased = current increase = bigger movement.
8) increasing distance of poles in magnet = decrease movement of wire = decreases magnetic field.
9) make wire bounce in other direction = change both = no reaction.
10) finding direction of force = flemmings left hand rule…..
THUMB = direction of force
1st FINGER = direction of field (from N to S)\
2nd finger= current direction (from + to -