A short ppt on medical physics

1. Basic electrical components
Submitted to Dr.Amna
Submitted by
Roll # 7,13,14,38,39.40,42,45,46,47,48.
Medical Physics Presentation

2. Transformer
 An Electrical instrument which is used to
alternating emf in to larger or smaller alternating
emf or to render a current earth-free.
 Working Principle: It works on principle of
mutual induction.
 Construction: It is made up of two coil
1. Primary Coil:
Is in which input alternating emf is
introduced.
2. Secondary Coil: From which output emf is
drawn.

4. Working of
Transformer
Two coils are magnetically
connected. There is no electrical
connection.
An alternating current is passed
through the primary coil and this
setsup a varying magnetic field,
which passes to secondary coil
by electromagnetic induction and

5. Ns/Np = Vs/Vp
On basis of numbers of turns transformer is
divided into two types.
1. Set up Transformer
2. Set down Transformer
Set up Transformer:
Ns> Np .then Vs > Vp.
Set Down Transformer:
Ns< Np . Then Vs<Vp

6. Set up
Transformer
Set down
Transformer

7. Ideal Power Transformer:
Power input = Power output
P=Vi
Vp Ip = Vs Is
Vs/ Vp = Ip /Is
Even Ratio Transformer:
If Np = Ns
Then
Vf = Vp

8. Power Loss of Tranformer:
Power is lost in two ways
1. Eddy Current
2. Hysteris Loss

9. Eddy Current:
Induced current set up perpendicular
to flux is eddy current. It causes
1.Power drespation
2.Heating core material.
Hysteris loss:
It is energy to magnetic and
demagnetic the core material in
each cycle of A.c

10. Minimizing the power loss:
1.Insulation is provided.
2.Resistance between primary coil
and secondary coil should be
minimize.
Efficiency of Transformer:
Pout< Pin
E= output power/Input power *100
E

11. Rendering a Current –Earth free:
Electricity produced by dynamo and
consumer supplied by live wire, it is
at high potential.
Neutral –Wire
It is at zero potential
Earth-Wire:
Supplies current to instrument.

12. If live earth wire accidently meet
,current will flow, and if person
touches that connection he will
recieve shock.
Transformer reduces Earth shocks.
Other Types of Transformer
1. Auto Transformer
2. variable transformer

13. Auto Transformer
Consist of single coil of wire with four
contecting points coming to it.
VariableTransformer
Length of coil can be changed.