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3 years ago

In the circuit shown below, 0.25 A of current flows through a 20-Ω resistor. How much voltage is needed to produce this current?

Physics

1 answer:

balu736 [363]3 years ago

5 0

Answer:

D 5 V

Explanation:

Without seeing the whole circuit it is impossible to say for certain.

However the simplest circuit would produce a value of

FV = IR = 0.25(20) = 5 v

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If a voltmeter has a less than ideal resistance, say 1 MΩ, and is used to measure the voltage across a resistor of a comparable

Naddik [55]

Answer:

As the difference between the resistance of voltmeter and the resistance being measured gets reduced the error in the reading of the voltmeter gets increased.

Explanation:

An ideal voltmeter has infinite parallel resistance and because of this it doesn't draw any current from the circuit of measurement which means it will measure the exact voltage across the elements.

But practically speaking, a real voltmeter doesn't has infinite resistance therefore, all the practical voltmeters face loading effect to some extent.

As the difference between the resistance of voltmeter and the resistance being measured gets reduced the error in the reading of the voltmeter gets increased. This is why we want to have a greater value of voltmeter resistance, ideally infinite so that the corresponding error is minimized.

Lets consider the given scenario,

A voltmeter has 1 MΩ parallel resistance and the resistance of of measuring element is 500 kΩ or 0.5 MΩ

lets suppose the supplied voltage is 1 V.

First lets assume that the voltmeter is ideal and it has infinite resistance, so in this case voltmeter will measure a voltage of 1 V across the 0.5 MΩ resistor.

Now consider the loading effect, when we connect the voltmeter across the 0.5 MΩ resistor they both become parallel so the resistance is

R = (1*0.5)/(1+0.5)

R = 0.33 MΩ

As you can see the voltmeter will see a reduced resistance and the corresponding voltage also reduces because resistance and voltage are directly proportional.

Therefore, it is preferred to have a very high parallel resistance of the voltmeter.

8 0

3 years ago

You want the current amplitude through a inductor with an inductance of 4.30 mH (part of the circuitry for a radio receiver) to

White raven [17]

Answer:

$f=1480.52 Hz$

Explanation:

For the circuit of the radio knowing the voltage in a inductor is VL and the relation of element is:

$V_L=I*Z_L*w$

Where $I= 300mA$ , $Z_L=4.3mH$ , $V_L= 12V$ and $w=2\pi *f$

Knowing that the frequency influence in the performance of the inductor so:

$V_L=I*Z_L*2\pi *f$

Solve to f'

$f=\frac{V_L}{I*Z_L*2\pi } =\frac{12v}{300mA*43.mH*2\pi}$

$f=1480.52 Hz$

4 0

3 years ago

If vector A is along 300 then _A will be along?

Marina CMI [18]

Answer:it will be 150 you divide by two

Explanation: hope it helps

3 0

3 years ago

When is evidence considered scientific?

ra1l [238]

When it has been proven by science to be true.

8 0

4 years ago

Why are the parts of an atom that electrons occupy called electron clouds?

Anna [14]

Because it's literally impossible to tell exactly where something that size is
located at any particular time.

And that's NOT because it's so small that we can't see it. It's because any
material object behaves as if it's made of waves, and the smaller the object is,
the more the size of its waves get to be like the same size as the object.
When you get down to things the size of subatomic particles, it doesn't make
sense any more to try and talk about where the particle actually "is", and we only
talk about the waves that define it, and how the waves all combine to become a
cloud of <em><u>probability</u></em> of where the particle is.

I know it sounds weird. But that's the way it is. Sorry.

8 0

3 years ago