**Controlling
The Real World With Computers**

::. Control And Embedded Systems .::

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Reading A Schematic & Basic Electronics

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Programming Part 1

**How
to Read a Schematic And Basic Electronics Test Answers**

1. B) Schematic

2. D) Switch

3. A) Resistor

4. E) Ohm, B) Ohm's Law

5. A) Amperes (or Amps), E) Milliamps (or Ma or ma)

6. C) Capacitors

7. B) Diode

8. D) Integrated Circuits

9. B) Operational Amplifier

10. This shows unconnected conductors.

11. This is a resistor.

12. This is a switch.

13. This is connected conductors.

14. This is a capacitor.

15. This is a diode.

16. This is the symbol for ground.

17. Ohm's Law: V = IR

18. I = 4, R = 10 so V = IR = 40 Volts

19. V = 12, R = 6 so I = V/R = 2 Amps

20. I = 75, V = 150K Volts so R = V/I = 150K/75 = 2K Ohms

21. P = VI = 150K * 75 = 11,250,000 Watts

22. 25K ohms

So,
the total resistance in the above circuit = __3000 ohms __

Now, remember that the current in a circuit = I = V/R.

The voltage is __3 volts __

So, remembering to write the equation first, plug in the values to get the current:

I = __V/R __= __3/3000__
= __1 ma __

Since all three resistors are
1000 ohms in the above circuit, there is a total of 3000 ohms, and I
= 3/3000 = 1ma. Remember, ma means milliamps or thousandths of an
amp, so 1ma is the same as 1/1000^{th}
of an amp. Now, to find the voltage across each 1K resistor, use V =
IR.

So, the **calculated**
voltage across each resistor =

V = IR = __1ma
* 1000__ = __1
volt__

Would including a 10K resistor work? No, because that would make the whole circuit more than 10K ohms.

1,385,247 ^{0}
**= **__1 __(__ anything__
raised
to the power of 0 is 1)

1
X 10^{3 =
}__1000
__(any
time you have 1 x 10 raised to a power, just write down 1, then the
number of zeros indicated by the exponent – 3 in this case)

.1ma
= __1/10000 __amps
(remember that ma means milliamps, and that mili means 1/1000^{th}.
This is 1/10^{th}
of that, which is 1/10000)

10^{1}
= __10 __(anything
raised to the power of 1 is itself)

10^{-4}
= __.0001 or 1/10000
__(remember
to start with a 1 followed by a decimal, then move the decimal to the
left the number of places shown by the negative exponent)

For the number 432.178,

the
4 is in the __100 __s
place,

the
7 is in the __1/100 __s
place, and

the
8 is in the __1/1000 __s
place.

x^{y0}
= x
raised to the power of y which is raised to the power of 0 = __x __

Work from right to left: y raised to the power of 0 is 1, then x raised to the power of 1 is x.

From the parallel circuit problem: But
since you know the voltage, you can use the rules for a parallel
circuit and Ohm's law for resistance and current. So calculate the
following. Remember, the voltage is 3 volts across each resistor.
Also remember to write Ohm's law for current first, which is __I
= V/R __:

Current
through R1: __I
= V/R __=
__3/30K__
= __.1
ma __(.0001
amp)

Current
through R2: __I = V/R __= __3/300 __= __.01__ __amp __

Current
through R3: __I
= V/R __=
__3/3K__
= __1
ma__
(.001 amp)

Total
current through all 3 = __11.1
ma__
(.0111 amp)

Since
you know the source voltage is 3 volts and you know the total
current, you can calculate the combined resistance using Ohm's law
for resistance, which is __R=V/I__
:

R_{total}
= __R=V/I__
= 3/.0111 = 270.270 ohms rounded off

Notice that the resulting value is less than the lowest value in the circuit.

This means the answer is reasonable, since the parallel value must be less than the lowest value.

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Reading A Schematic & Basic Electronics

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Programming Part 1

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