The document discusses amplifiers and attenuators. It defines an amplifier as a device that increases the value of a signal, like voltage, current, or power. Examples given include audio amplifiers in sound systems and personal radios. Attenuators are the opposite, decreasing the value of a signal, and are used when a strong signal needs to be lowered, like in mobile towers receiving calls. Both amplifiers and attenuators have many applications, from sound systems to power grids, and transistors are commonly used as amplifiers for their efficiency over transformers with small signals.

1. Amplifier

2. What is an Amplifier?
Where do we require amplification?
Do we ever require an Attenuator?
Transformer can also amplify you know,
then why transistor?

3. What is an amplifier?
 “Amplify” means to increase the value of something .
 The machine which amplifies something is an amplifier.
 A teacher wants that all students can hear his lecture.
To ensure this , he uses a device like this.

4.  An amplifier is an instrument that enlarges or
extends power, current, or voltage.We are
using the amplifier for sound.
Function of Amplifier

5. Practical Uses of Amplifier
 We use lever to lift something .This is also one
kind of amplification . Here, a heavy object is
being lifted applying less force .

6. Amplifiers In Action
 Audio amplifiers are used in sound systems,
car horns , and personal radios. Bands also
use amplifiers to create a louder sound.

7. An Important Application!
 In radio stations, it is required to amplify
signal . Because radio signal is distributed at a
long distance.

8. Concept of Attenuator
 Sometimes it happens that we need to
decrease the value of a signal .Then we need
to perform reverse operation of
amplification.
 We shall say the reverse operation of
amplification is “ Attenuation”.

9. Practical Example!
 While crossing a speed-breaker on a bi-cycle,
we feel a mild thrust because there are
springs under the seat .This thrust is less than
bi-cycle in a bus.

10. Definition of Attenuator
 While an amplifier provides gain, an
attenuator provides a gain less than 1, or a
loss.

11. Necessity of Attenuator
 In a mobile tower , it is required to lower the
signal when an incoming call is received.
Because we can’t tolerate such a high volume
sound.

12. Transformers & Amplification
 At power station, transformers are used to
amplify voltage for current supply with a
minimum loss.Then , automatically current
gets reduced to keep the power constant .

13. Transistor as Amplifier
 Transistor can amplify both voltage & current
as it works with less power than a transformer .

14. Transistor instead of
Transformer
 Transformer is required where large signal is
used. For example, line voltage ( 33 KV) is
transformed to home voltage (220V).
 Transistor is used where small signal needs to
be amplified . For example , loudspeaker
amplifies microphone’s weak signal(1 mV)
 BothTransformer &Transistor are used
according to their magnitude of signal.

15. Let’s Think…
 In daily life , there are a lot of examples of
amplifiers & attenuators . can you mention
some of them ?
Just think about it…

17. Presented By
 Tarik RezaToha,1205082
 Md. Abdullah Al Alamin,1205084
 Amit Chakraborty,1205086
 Sazzad Hossain,1205088
 Md. Abdullah Al Maruf,1205090
 Md. Mehdi Rahman,1205118
Dept. of CSE,BUET