6d) Electromagnetic Induction

Electromagnetic Induction: The creation of a voltage (and maybe a current) in a wire which is experiencing a change in magnetic field.

To get a bigger voltage....
Increase the strength of the magnet
Increase the speed of movement
Increase the number of turns on the coil

You can reverse the current direction:
reverse the magnetic field by flipping the magnet
switching/ change the direction of wire movement

Only get an induced current if it is part of a complete circuit, otherwise it would be an induced voltage (will always be an induced voltage)

Factors that increase the amount of electricity being produced: strength of magnetic field, number of coils in wire, speed of rotations

Paper Two- Transformers 

Is a device which can increase or decrease the value of an alternating voltage by having different number of turns on input and output sides. It consists of two coils wound round an soft iron core. 

    

Step-Up Transformers

• increases the voltage by more turns on the secondary coil than primary

Step-Down Transformers

• decreases the voltage by having more turns on the primary coil than secondary

input(primary)voltage/ output(secondary)voltage =  primary turns/ secondary turns 

Vp/Vs = Np/ Ns 

Transformer efficiency:

= Power output from secondary coil / Power input to primary coil 

= (I_sV_s) / (I_pV_p) x 100% 

(I_sV_s) / (I_pV_p)

 when a transformer is supplying current, it is almost 100% efficient