Material: semi - conductor or metal?

[Pushoam]

Homework Statement

Homework Equations

The Attempt at a Solution

Since the dependence of resistance upon the tem. is different for metal and semi - conductor ( increase of tem. decreases semi - con. resistivity while increases metal's resistivity.), option c is not the right answer.
Since the electrical conductivity is different for semi - conductor and metal and magnetic field could be taken as an electric field in a different inertial frame, option d will also reveal the nature of the material.

Is absorption spectrum of a metal and semi - conductor categorically different for the given energy - range?
Isn't absorption spectrum unique for every material?

Can the frequecy of the power source reveal the nature of the material?About q.no.39,
the digital voltmeter has to show at least four digits e.g. 4.006 V.
The first digit could be anything between 0 and 5, while the other three digits could be anything between to 9.
To represent a no. 9, I need four bits for 1001. Similarly, to represent each of the three digits, I need 12 bits. And to represent the first digit, I need three bits. So, I need 15 bits.
Or do I have to convert 5.000 into decimal system and then see how many bits are needed?

 

[cnh1995]

Can the frequecy of the power source reveal the nature of the material?

No.

About question 39:
The minimum voltage that the meter can display is 5mV, which means 1 step= 5mV.
Calculate the maximum number of steps required.
What minimum number of bits is needed to get this number of steps?

 

[Pushoam]

No.

About question 39:
The minimum voltage that the meter can display is 5mV, which means 1 step= 5mV.
Calculate the maximum number of steps required.
What minimum number of bits is needed to get this number of steps?

10 bits are needed to represent this no. 1000.
For each step, the voltmeter has to show a different signal i.e. a different combination of bits. So, the cobinations of these 10 bits show no. from 0 - 1024. How does these no. got converted into , say, 4.334 mV (as the voltmeter has to show this not from no. among 1 - 1000?

 

[cnh1995]

10 bits are needed to represent this no. 1000.
For each step, the voltmeter has to show a different signal i.e. a different combination of bits. So, the cobinations of these 10 bits show no. from 0 - 1024. How does these no. got converted into , say, 4.334 mV (as the voltmeter has to show this not from no. among 1 - 1000?

Any voltage below 5mV will be read as 0.

 

[Pushoam]

Any voltage below 5mV will be read as 0.

Sorry, I wanted to ask how will the voltmeter show 4.435V instead of a no. among 0 - 1024?

 

[cnh1995]

Sorry, I wanted to ask how will the voltmeter show 4.435V instead of a no. among 0 - 1024?

Number of steps= 4.435/5mV=887.
The ADC in the voltmeter will convert 887 into digital form (10 bit) and feed it to the seven-segment display through some decoder circuitry. The voltmeter will display 4.435 on its screen (decimal point is a part of the seven-segment display).

 

[Pushoam]

Number of steps= 4.435/5mV=887.
The ADC in the voltmeter will convert 887 into digital form (10 bit) and feed it to the seven-segment display through some decoder circuitry. The voltmeter will display 4.435 on its screen (decimal point is a part of the seven-segment display).

What I understood is:
We have to generate 1000 different signals for each step as we have to show 1000 different no. on the display.Using 10 bits, we can show 1000 different binary numbers. Then, using some decoder circuitry, we convert this 1000 different binary numbers into 1000 different decimal numbers. To represent the required decimal is the job of the decoder circuit which is not the part of our question.
Is this correct?

 

[cnh1995]

What I understood is:
We have to generate 1000 different signals for each step as we have to show 1000 different no. on the display.Using 10 bits, we can show 1000 different binary numbers. Then, using some decoder circuitry, we convert this 1000 different binary numbers into 1000 different decimal numbers. To represent the required decimal is the job of the decoder circuit which is not the part of our question.
Is this correct?

We need 0-1024 numbers (steps), which correspond to 0-5.12V, with 5mV/step resolution. And yes, the question is all about finding how many bits are required at the ADC output.

 

[Abhishek kumar]

What I understood is:
We have to generate 1000 different signals for each step as we have to show 1000 different no. on the display.Using 10 bits, we can show 1000 different binary numbers. Then, using some decoder circuitry, we convert this 1000 different binary numbers into 1000 different decimal numbers. To represent the required decimal is the job of the decoder circuit which is not the part of our question.
Is this correct?

Here problem is restricted by saying precision of 5mv means so there is only 1000 sets of voltage

 

[Pushoam]

ADC output.

What is ADC?

Thanks to all for helping me.

 

[cnh1995]

What is ADC?

Analog to Digital Converter.

 

[Pushoam]

Thank you.