Chapter 3: Electromagnetism1. Diagram 4 shows the telephone ear piece which receives a varying current from thetelephone line. The permanent magnet attracts the magnet alloy diaphragm. The varyin current in the coils of the electromagnet changes the strength of the magnetic field .With the use of apparatus such as a soft iron rod, insulated copper wire, retort stand and other apparatus, describe one experiment to investigate the hypothesis stated in 4(b).

InferenceThe strength of the electromagnet is depends on the current

HypothesisThe higher the current flowing through the solenoid, the stronger the electromagnet

AimTo study the relationship between the current and the strength of the electromagnet

Variable:ManipulatedRespondingFixed MV CurrentRV Number of pins attractedFV Number of coils, type of pins used

List of apparatusMetal rod, ammeter, rheostat, pins in a dish, power supply,insulated copper wires, retort stand, wooden clamp

Arrangement

Procedures1.Setup the apparatus as the diagram shown.2. Adjust the rheostat to get 1.0 A current. 3. The dish of pins is placed near to the end of the electromagnet, then removed. Count and record the number of pins attracted.4. The experiment is repeated with current values of 2.0 A, 3.0 A, 4.0 A, and 5.0 A.

TabulateCurrent, I/ANumber of pins attracted, n

Graph n

I/A

2. Diagram 4.1 and 4.2 show the electric bell which are connected to the similar batteries.

With use of apparatus such as a insulated copper wire , small iron pins and other apparatus, describe an experiment to investigate the hypothesis stated in 3(b)

InferenceMagnetic field strength depends on the number of turns

HypothesisThe greater the number of turns, the greater the magnetic field strength

AimTo investigate the relationship between magnetic field strength andnumber of turn on the coil

Variable:ManipulatedRespondingFixed MV Number of turnsRV Magnetic field strengthFV size of current// type of core

List of apparatusRetort stand, soft iron core, connector wire, PVC insulated copper wire,small iron pin, ammeter, rheostat , battery/ power supply

Arrangement

Procedures1.Setup the apparatus as the diagram shown.2. The soft iron core is wound with 10 turns of insulated copper wire.3. The dish of pins is placed near to the end of the electromagnet, then removed. Count and record the number of pins attracted.4. Repeat the experiment by using 20, 30, 40, and 50 turns.

TabulateNumber of turns/ turnsNumber of pin attracted/ pieces

10

20

30

40

50

Graph Number of pin attracted/ pieces

Number of turns/ turns

3. Diagram 4.1 and Diagram 4.2 show a driller. In Diagram 4.1, the 4.5 V batteries are used and the drill bit penetrated more into the wall. In Diagram 4.2, the 3.0 V batteries are used and the drill bit penetrated less into the wall.

With the use of apparatus such as a d.c. power supply, magnets, C-shaped iron yoke, bare copper wire, connecting wires and other apparatus.InferenceThe force depends on the current

HypothesisThe greater the current in the conductor, the greater the force/ penetration distance

AimTo study the relationship between the current in the conductor and the force/ distance travelled

Variable:ManipulatedRespondingFixed MV Current/ VoltageRV Distance travelledFV Strength of magnet / Number of magnets

List of apparatusMetre rule, sliding copper wire, d.c. power supply, connecting wires, U-shaped iron yoke, magnet, ammeter and bare copper wire

Arrangement

Procedures1.Setup the apparatus as the diagram shown.2. Adjust the rheostat to get current of 1.0 A.3. Measure the distance travelled of the sliding wire.4. Repeat the experiment with current of 2.0 A, 3.0 A, 4.0 A and 5.0A.

TabulateCurrent, I/ADistance travelled, d/cm

1.0

2.0

3.0

4.0

5.0

Graph I/A

d/cm

4. Diagram 1 and 2 show a cross section of a bicycle dynamo. Each dynamo has a magnet and a coil of insulated copper wire. The output of both bicycle dynamo are connected to a bicycle lamp. Diagram 1 shows the bicycle dynamo has less turns of coil wire than bicycle dynamo in Diagram 2. With the use of apparatus such as insulated copper wire, ammeter bar magnet and other apparatus.

InferenceNumber of turns of the coil/ change of magnetic flux influence the change of magnetic flux / induced current

HypothesisNumber of turns of the coil/ change of magnetic flux increases, induced current/ current increases

AimTo determine the relationship between the number of turns of the coil and changes of induced current/ change of magnetic flux / current

Variable:ManipulatedRespondingFixed MV number of turns of the coil RV Current FV Speed

List of apparatuscopper wire, cardboard, bar magnet, milliammeter and ruler

Arrangement

Procedures1.Setup the apparatus as the diagram shown.2. By using 10 turns of coil, the magnet is released from a fixed height and falls through the coil.3. Record the reading of ammeter.4. Repeat the experiment by using 20, 30, 40, and 50 turns.

TabulateNumber of turns, nCurrent, I/mA

10

20

30

40

50

Graph I/mA

n

5. Diagram shows a step down transformer. A primary coil is connected to the input supply 240V a.c. Diagram 4.1(a) and diagram 4.1(b) shows a bulb that is connected to a secondary coil. It is observed that the brightness of the bulb in diagram 4.1(b) is brighter than in diagram 4.1(a).

With the use of apparatus such as coil, voltmeter, two pieces soft iron core and other suitable apparatus.InferenceThe number of turns of wire in the secondary coil affects the output voltage

HypothesisThe greater the number of turns of wire in the secondary coil, the greater theoutput voltage

AimTo investigate the relationship between number of turns of wire in the secondarycoil and the output voltage

Variable:ManipulatedRespondingFixed MV number of turns of wire in secondary coil, N RV output voltage, VFV The number of turns of wire in the primary coil

List of apparatusVoltmeter, coil, soft iron core, au power supply

Arrangement

Procedures1. Setup the apparatus as the diagram shown.2. 100 turns of wire is wound on the secondary coil of a transformer.3. The switch is on and the output voltage is measured by using a voltmeter.4. The experiment is repeated by winding the wire on secondary coil with 200 turns, 300 turns, 400 turns and 500 turns.

TabulateNumber of turns, nOutput Voltage, V/V

100

200

300

400

500

Graph V/V

n

Inference

Hypothesis

Aim

Variable:ManipulatedRespondingFixed MV RV FV

List of apparatus

Arrangement

Procedures1.Setup the apparatus as the diagram shown.6. By using 10 turns of coil, the magnet is released from a fixed height and falls through the coil.7. Record the reading of ammeter.4. Repeat the experiment by using 20, 30, 40, and 50 turns.

TabulateNumber of turns, nCurrent, I/mA

Graph I/mA

n