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3 years ago

5

True or False: (2 points) If a scientist finds evidence that contradicts a hypothesis, law, or principle, then it is their choic

e whether to change the hypothesis, law, or principle.

1 answer:

Furkat [3]3 years ago

6 0

Answer:

True

Explanation:

A hypothesis is an educated guess, it does not have to be right.

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As water heats in a pot on a stove, it might produce some mist above its surface right before the water begins to roll. What is

mr_godi [17]

When a liquid is heated, the molecules gain kinetic energy. As the liquid begins to boil they have enough energy to break the intermolecular attractions between their neighbors. This happens first at the surface before the volume below has enough energy to boil. Thus you see high energy water molecules escaping from the surface as mist.

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4 years ago

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A 217 Ω resistor, a 0.875 H inductor, and a 6.75 μF capacitor are connected in series across a voltage source that has voltage a

Nataly [62]

For an AC circuit:

I = V/Z

V = AC source voltage, I = total AC current, Z = total impedance

Note: We will be dealing with impedances which take on complex values where j is the square root of -1. All phasor angles are given in radians.

For a resistor R, inductor L, and capacitor C, their impedances are given by:

$Z_{R}$ = R

R = resistance

$Z_{L}$ = jωL

ω = voltage source angular frequency, L = inductance

$Z_{C}$ = -j/(ωC)

ω = voltage source angular frequency, C = capacitance

Given values:

R = 217Ω, L = 0.875H, C = 6.75×10⁻⁶F, ω = 220rad/s

Plug in and calculate the impedances:

$Z_{R}$ = 217Ω

$Z_{L}$ = j(220)(0.875) = j192.5Ω

$Z_{C}$ = -j/(220×6.75×10⁻⁶) = -j673.4Ω

Add up the impedances to get the total impedance Z, then convert Z to polar form:

Z = $Z_{R}$ + $Z_{L}$ + $Z_{C}$

Z = 217 + j192.5 - j673.4

Z = (217-j480.9)Ω

Z = (527.6∠-1.147)Ω

Back to I = V/Z

Given values:

V = (30.0∠0+220t)V (assume 0 initial phase, and t = time)

Z = (527.6∠-1.147)Ω (from previous computation)

Plug in and solve for I:

I = (30.0∠0+220t)/(527.6∠-1.147)

I = (0.0569∠1.147+220t)A

To get the voltages of each individual component, we'll just multiply I and each of their impedances:

$v_{R}$ = I× $Z_{R}$

$v_{L}$ = I× $Z_{L}$

$v_{C}$ = I× $Z_{C}$

Given values:

I = (0.0569∠1.147+220t)A

$Z_{R}$ = 217Ω = (217∠0)Ω

$Z_{L}$ = j192.5Ω = (192.5∠π/2)Ω

$Z_{C}$ = -j673.4Ω = (673.4∠-π/2)Ω

Plug in and calculate each component's voltage:

$v_{R}$ = (0.0569∠1.147+220t)(217∠0) = (12.35∠1.147+220t)V

$v_{L}$ = (0.0569∠1.147+220t)(192.5∠π/2) = (10.95∠2.718+220t)V

$v_{C}$ = (0.0569∠1.147+220t)(673.4∠-π/2) = (38.32∠-0.4238+220t)V

Now we have the total and individual voltages as functions of time:

V = (30.0∠0+220t)V

$v_{R}$ = (12.35∠1.147+220t)V

$v_{L}$ = (10.95∠2.718+220t)V

$v_{C}$ = (38.32∠-0.4238+220t)V

Plug in t = 22.0×10⁻³s into these values and take the real component (amplitude multiplied by the cosine of the phase) to determine the real voltage values at this point in time:

V = 30.0cos(0+220(22.0×10⁻³)) = 3.82V

$v_{R}$ = 12.35cos(1.147+220(22.0×10⁻³)) = 11.8V

$v_{L}$ = 10.95cos(2.718+220(22.0×10⁻³)) = 3.19V

$v_{C}$ = 38.32cos(-0.4238+220(22.0×10⁻³)) = -11.2V

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3 years ago

An electrical current flowing through a filament bulb causes it to get hot. Explain why this

sergij07 [2.7K]

Answer:

The reason the filament heats up is because it has a high resistance, which means that as electrons move through the filament, they lose a lot of energy.

First, what is current? Current is comprised of electrons moving through an electric field from a high electric potential to a lower potential. For the current to decrease then, something would need to happen to the electrons that go into the light bulb. If 1 electron goes into the light bulb, then at the end of everything I need to still have 1 electron someplace. So how do electrons passing through the bulb make light?

Incandescent light bulbs have a small filament which when heated begins to glow and emit light. The reason the filament heats up is because it has a high resistance, which means that as electrons move through the filament, they lose a lot of energy. You can think of it as walking on a sidewalk compared to walking in waist deep water. A wire is like a sidewalk. It has some resistance, but it is so tiny that it can generally be ignored which is why wires are useful in electronic circuits. The high resistance of the light bulb is like trying to walk through waist deep water. Here energy is being taken from the electrons because of the interactions with the atoms in filament which causes those atoms to heat up, which in turn makes them emit light.

The light bulb is not doing anything to the electrons, so we expect then that any electrons going into the bulb should come out the other side. Since current is just flowing electrons, current stays the same.

Since current is the same on both sides, we know that the electrons are all moving together. Think of it like being in a big loop of people. Since everyone is in a big line you could imagine that you could only move as fast as the slowest person in the line. If everyone is on a big loop of sidewalk then everyone could run around in a circle. This is like having a large current in a loop of wire, or what we call a short. To put the equivalent of a lightbulb into our human circuit, imagine that one section of the sidewalk dips into a pool of water. Now everyone is stuck going as fast as the people trudging through the water. This is why current everywhere in a circuit is smaller when a resistor is introduced. As people trudge through the water they have to work hard to get through the water and they use energy. In a circuit, this energy comes from the voltage source, like a battery. The battery loses energy because it has to "pull" the electrons through the high resistance, and this is why the voltage drops across the light bulb

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3 years ago

Which features form when magma cools beneath earths surface

Sholpan [36]

<h2>Answer:</h2>

<u>The features form when magma cools beneath earths surface are Volcanic necks and Dome mountains</u>

<h2>Explanation:</h2>

Volcanic Mountains are formed when molten rock (magma) deep within the earth, erupts, and after cooling it piles upon the surface. Similarly A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. So these two are the features that are formed when magma cools beneath earths surface

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3 years ago

The device that measures current in a wire by using the deflections of an electromagnet in an external magnetic field is

Law Incorporation [45]

A galvanometer hope this helps

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3 years ago

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