## Monday, June 29, 2009

### Factors That Afect The Magnitude of Induced CurrentA

1. Explain factors that affect the magnitude of the induced current.

The magnitude of the induced current depends on the rate of change of magnetic flux or the rate of cutting of the magnetic field lines.

The factors that affect the magnitude of the induced current are,

i. the number of turns of the coil
As the number of turns increases, the magnitude of the induced current increases.

ii. the speed of the relative motion of the conductor and the magnetic field
As the speed of the relative motion of the magnet increases the magnitude of the induced current increases.

iii. the strength of the magnet
Increasing the strength of the magnet, will increase the magnitude of the induced current.

2. Describe applications of electromagnetic induction
Electromagnetic induction is applied in the working principles of a d.c. and a.c. generator.

a.c. generator

d.c generator

*compare the number of carbon brush, accumulator and current produced.

3. Compare direct current and alternating current

Alternating current (a.c.) changes in magnitude and direction,

while direct current (d.c.) has a fixed magnitude and flows only in one direction.

## Sunday, June 28, 2009

### Electromagnetic induction

1.When a conductor cuts the magnetic flux of a magnet, a current is induced in the conductor.
• when the wire moves parallel to the magnetic field, mo magnetic flux is being cut, no e.m.f. is induced, thus there is no inducted current flowing in the circuit.

2. The direction of the induced current flow in a straight conductor can be determined using Fleming's Right Hand Rule.
• the thumb shows the direction of motion of the wire or the direction of force
• the forefinger points in the direction of the magnetic field,
• the second finger points in the direction of the induced current.

3. The direction of induced current flowing in a solenoid depends on the direction of the relative movement and the polarity of the magnet.
• A the North pole of the magnet moves towards the solenoid, the galvanometer pointer deflects to the right.
• From end A of the solenoid, the induced current flows in the anticlockwise direction.
• End A becomes the North pole of the solenoid.
• From end B of the solenoid, the induced current flows in the clockwise direction.
• End B becomes the South pole of the solenoid.
• The direction of the induced current in a solenoid obeys Lenz's Law.
• Lenz's Law states that the direction of the induced current in the solenoid is such that it opposes the change producing it.
4. Application of electromagnetic induction.
- Dynamo,turbine in hydro plant , wind mill etc.

## Wednesday, June 3, 2009

### Kem Muhibah 2009

Perkhemahan unit beruniform ( kem muhibah) tahun 2009 telah diadakan pada 29 mei 2009 sehingga 31 mei 2009 , iaitu selama 3 hari 2 malam di Impiam resort Batu 18 Hulu Langat, Selangor.
aktiviti yang dijalankan termasuk :
> merentas halangan
> night walk
> jungle tracking
> ceramah motivasi
> permaianan
makan 6 kali sehari, tidur mestilah di dalam khemah.membentuk kumpulan

permainan ice breaking
Yang menghadap camera : "ambil gambar dulu..."
Seon : "apakah penyelesiaannya ?"
Joey :" ????"
makan bersama
mandi sungai
lost in the jungle