$\epsilon = \frac{W}{Q}$

$V = \frac{W}{Q}$

$I = \frac{Q}{t}$

$R = \frac{V}{I}$ (IMPT: It’s ratio, NOT gradient)

$R = \frac{\rho L}{A}$

Series: $R_{total} = R_{1} + R_{2} + …$

Parallel: $\frac{1}{R_{total}} = \frac{1}{R_{1}} + \frac{1}{R_{2}} + …$

$P = VI = I^{2}R = \frac{V^{2}}{R}$

$E = Pt = (VI)t$

**Electromagnetic force and Electromagnetic Induction:**

Transformer:

$\frac{V_{p}}{V_{s}} = \frac{N_{p}}{N_{s}}$

$V_{p}I_{p} = V_{s}I_{s}$

Operation of transformer:

- Alternating current supplied to primary coil
- Alternating current causes iron core to magnetise and magnetic field to change
- Magnetic fields follow iron core and link to secondary coil
- Hence, emf is induced in the secondary coil by electromagnetic induction due to the changing magnetic fields

Left hand rule for motor:

Right hand rule for generator/dynamo:

Right hand grip rule: (To determine direction of magnetic field/current)

Ways to increase emf in solenoid:

- Use a stronger magnet
- Increase the speed of moving the magnet
- Increase the number of turns in the coil

Ways to increase emf in a.c. generator:

- Decrease distance between magnet and coil
- Use a stronger magnet
- Increase frequency of rotation of the coil (Double freq. = double max. e.m.f. and halving T)
- Increase number of turns in the coil (Double no. of turns = double max e.m.f.)

### Radioactivity & The Nuclear Atom

Half life: (n is number of half-life)

$$\frac{N_{\text{final}}}{N_{\text{initial}}} = \left( \frac{1}{2} \right)^{n}$$

OGU JAMES OKUDU scribbled

I WANT TO BE BRAVE HOW WILL I DO?

mercie joe scribbled

what about the electrical parts

Bryan scribbled

you guys missed the entire chapter on electrical formulas

ekele scribbled

wow!!! tnxs.. d formular are jus ok..

wahab ullah scribbled

wonderful. this is the way to promote your level in physics.

Toluwanimi scribbled

wonderful physics

issa.m scribbled

Truly Physics unravels the wonders of the world we live. Yes it is wonderful

wahab ullah scribbled

tnk you.this is very sufficient forum .