Để sử dụng nguồn điện xoay chiều 220V/50Hz thắp sáng bóng đèn 12V/3W, ta chọn điện trở giảm áp có giá trị:

Answers

Answer 1

Explanation:

Hi Linda,

How's it going?

Sorry I haven't been in touch for such a long time but I've had exams so I've been studying every free minute. Anyway, I'd love to hear all your news and I'm hoping we can get together soon to catch up. We just moved to a bigger flat so maybe you can come and visit one weekend?

How's the new job?

Looking forward to hearing from you!

Helga


Related Questions

Two identical loudspeakers 2.30 m apart are emitting sound waves into a room where the speed of sound is 340 m/s. Abby is standing 4.50 m in front of one of the speakers, perpendicular to the line joining the speakers, and hears a maximum in the intensity of the sound.

Required:
What is the lowest possible frequency of sound for which this is possible?

Answers

Answer:

Abby is standing (4.5^2 + 2.3^2)^1/2   from the far speaker

D2 = 5.05 m from the far speaker

The difference in distances from the speakers is

5.05 - 4.5 = .55 m     (Let y be wavelength, lambda)

n y = 4.5

(n + 1) y = 5.05 for the speakers to be in phase at smallest wavelength

y = .55 m          subtracting equations

f = v / y = 340 / .55 = 618 / sec     should be the smallest frequency

Choir members are traditionally grouped into four main vocal registers: bass,
tenor, alto, and soprano. Men with low-pitched voices tend to sing bass, while
those with slightly higher-pitched voices sing in the tenor range. Similarly,
women with low-pitched voices sing alto, while women with high-pitched
voices sing soprano. Which vocal register sings at the lowest frequency?
A. Bass
B. Alto
C. Soprano
D. Tenor

Answers

Answer:

The bass has the lowest frequency ,it only causes vibrations but at a lower frequency

The cation that is reabsorbed from the urine in response to aldosterone

Answers

Answer:

If decreased blood pressure is detected, the adrenal gland is stimulated by these stretch receptors to release aldosterone, which increases sodium reabsorption from the urine, sweat, and the gut. This causes increased osmolarity in the extracellular fluid, which will eventually return blood pressure toward normal.

Two loudspeakers placed 6.00 m apart are driven in phase by an audio oscillator having a frequency range from 1908 Hz to 2471 Hz. A point P is located 4.70 m from one loudspeaker and 3.60 m from the other speaker. At what frequency of the oscillator does the sound reaching point P interfere constructively

Answers

Answer:

2164 Hz

Explanation:

Since point P is 4.70 m away from one speaker and 3.60 m away from the other speaker, the path length difference ΔL = 4.70 m - 3.60 m = 1.1 m.

The path length difference ΔL = nλ for a constructive interference where n is an integer and λ = wavelength of sound from oscillator = v/f where v = speed of sound in air = 340 m/s and f = frequency of sound from oscillator.

So, ΔL = nλ = nv/f

So, the frequency from the oscillator is f = nv/ΔL

Substituting the values of v and ΔL into the equation, we have

f = nv/ΔL

f = n340 m/s/1.1 m

f = n309.09 /s

f = 309.09n Hz

We now insert values of n that will gives us a frequency in the range 1908 Hz to 2471 Hz.

The value of n that will give us a frequency in the range is n = 7

So, when n = 7,

f = 309.09n Hz

f = 309.091 × 7 Hz

f = 2163.64 Hz

f ≅ 2164 Hz

So, the frequency of the oscillator that will produce a constructive interference at P is 2164 Hz.

Monochromatic light is incident on a metal surface and electrons are ejected. If the intensity of the light is increased, what will happen to the ejection rate and maximum energy of the electrons

Answers

Answer:

Increase the rate and the same maximum energy of the electrons

Explanation:

According to the photoelectric effect we can say:

The number of electrons, or the electric current, has a linear behaviour with the intensity of the light and a constant behaviour whit the frequency. Therefore, the rate of electrons increases.

The kinetic energy of the ejected electrons has a linear dependence on the frequency of the light and has a constant behaviour with the intensity. So, we can say there is the same maximum energy.

I hope it helps you!

Outside a spherically symmetric charge distribution of net charge Q, Gauss's law can be used to show that the electric field at a given distance:___________.
A) must be directed inward.
B) acts like it originated in a point charge Q at the center of the distribution.
C) must be directed outward.
D) must be greater than zero.
E) must be zero.

Answers

Answer:

Q at the center of the distribution.

Explanation:

The Gauss's law is the law that relates to the distribution of electrical charges to the resulting electrical field. It states that a flux of electricity outside the arabatory closed surface is proportional to the electricitical harg enclosed by the surface.

a vector starts at the point (0.0) and ends at (2,-7) what is the magnitude of the displacement

Answers

Answer:

|x| = √53

Explanation:

We are told that the vector starts at the point (0.0) and ends at (2,-7) .

Thus, magnitude of displacement is;

|x| = √(((-7) - 0)² + (2 - 0)²)

|x| = √(49 + 4)

|x| = √53

A 15kg mass suspended from a ceiling is pulled aside with a horizontal force, F. Calculate the value of the tension.​

Answers

Answer:

147 Newtons

Explanation:

To find tension, you can use the formula Tension = (mass)(gravity)

*Gravity's acceleration = 9.8 m/s^2 because of Newton's law of universal gravitation*

T = (15kg)(9.8m/s^2)

  = 147 Newtons

Hope this helps! Best of luck <3

How to calculate voltage U1 ?

Please help!

Answers

Answer:

he is a baby art and design

Partial tides _______. Question 7 options: represent various components of local tides that are resolved mathematically are predicted individually are added together to predict the height and timing of astronomical tides All of the above are correct. Only a and c are correct.

Answers

Complete Question

Partial tides __________.

Question 7 options:  

a. represent various components of local tides that are resolved mathematically  

b. are added together to predict the height and timing of astronomical tides  

c. consist of 4 components due to the influence of celestial bodies  

d. consist of up to 60 components due to astronomical and non-astronomical factors  

e. All of the above except c are correct.

Answer:

Option E

Explanation:

Generally

Partial tides represent various components of local tides that are resolved mathematically

Partial tides  are added together to predict the height and timing of astronomical tides

Partial tides consist of up to 60 components due to astronomical and non-astronomical factors

But Partial tides do not consist of 4 components due to the influence of celestial bodies

Therefore

All of the above except c are correct.

Option E

4 motor car is approaching a road crossing with a speed of 75 km/hr. A onstable standing near the crossing hears the frequency of its horns 260 Hz. That is the real frequency of horn? The speed of sound in air = 332 m/s. [IOE]​

Answers

Answer:

181 is the answer I think so

Data related to Meena’s and Malini’s journey is given below, plot a graph of their
respective journey on a graph paper. You have already plotted Meena’s Journey during the
summer vacation. On the same graph paper, now plot Malini’s Journey.
PDF task 2
Please do this for me urgent I can give you extra points if someone answers this in less than 1 hour.

Answers

Answer:

download the pdf

Explanation:

A generator uses a coil that has 270 turns and a 0.48-T magnetic field. The frequency of this generator is 60.0 Hz, and its emf has an rms value of 120 V. Assuming that each turn of the coil is a square (an approximation), determine the length of the wire from which the coil is made.

Answers

Answer:

The total length of wire is 0.24 m.

Explanation:

Number of turns, N = 270

magnetic field, B = 0.48 T

frequency, f = 60 Hz

rms value of emf = 120 V

maximum value of emf, Vo = 1.414 x 120 = 169.68 V

let the area of square is A and the side is L.

The maximum emf is given by

Vo = N B A w

169.68 = 270 x 0.48 x A x 2 x 3.14 x 60

A = 3.5 x 10^-3 m^2

So,

L = 0.0589 m

Total length of wire, P = 4 L = 4 x 0.0589 = 0.24 m

When the lightbulbs were used as the resistors, you observed only a flash of light, as opposed to a continuous glow. Explain why that behavior is expected. After all, the light bulb is directly connected to the power supply.

Answers

Solution :

Whenever the lightbulbs are used as resistors, we throw the switch to the left. This allows the current to flow through the circuit which causes the bulb to glow and also the capacitor gets charged. When the capacitor gets fully charged, the electric field becomes constant between its two plates. Now there is no displacement current induced in the plates of the capacitor. The capacitor works as an open switch and the bulb gets switched off.

And thus the bulb flashes for the moment as opposed to continuous glow.

what are the limitation of clinical thermometer

Answers

Answer:

Their main disadvantage is that they are fairly easy to break and if they do, it results in small splinters of glass and the release of mercury which is quite toxic if absorbed into the body.

answer bhejo please please please​

Answers

Answer:

Various uses of water :

1. Water is used for daily purpose like cooking , bathing , cleaning and drinking.

2. Water used as a universal solvent.

3. water maintains the temperature of our body.

4. Water helps in digestion in our body.

5 .water is used in factories and industries.

6. Water is used to grow plants , vegetables and crops.

A 30-cm-diameter, 90-cm-high vertical cylindrical container is partially filled with 60-cm-high water. Now the cylinder is rotated at a constant angular speed of 180 rpm. Determine how much the liquid level at the center of the cylinder will drop as a result of this rotational motion.

Answers

Answer:

[tex]\triangle h_c =0.204m[/tex]

Explanation:

Diameter [tex]d=30cm[/tex]

Height [tex]h=90cm[/tex]

Fill height [tex]h_f=60cm[/tex]

Angular speed [tex]N=180rpm[/tex]

Generally the equation for Angular velocity is mathematically given by

[tex]\omega=\frac{2 \pi*N}{60}[/tex]

[tex]\omega=\frac{2 \pi*180}{60}[/tex]

[tex]\omega=18.85rads/s[/tex]

Generally the equation for Liquid surface is mathematically given by

[tex]\mu_s=h*\frac{\omega^2*0.15^2}{4*9.81}[/tex]

[tex]\mu_s=0.396m[/tex]

Therefore the liquid drop at center due to rotation is

[tex]\triangle h_c =h-\mu_s[/tex]

[tex]\triangle h_c =0.60-0.396[/tex]

[tex]\triangle h_c =0.204m[/tex]

The voltage in an EBW operation is 45 kV. The beam current is 50 milliamp. The electron beam is focused on a circular area that is 0.50 mm in diameter. The heat transfer factor is 0.87. Calculate the average power density in the area in watt/mm2.

Answers

Answer:

[tex]P_d=6203.223062W/mm^2[/tex]

Explanation:

From the question we are told that:

Voltage [tex]V=45kV[/tex]

Current [tex]I=50mAmp[/tex]

Diameter  [tex]d=0.50mm[/tex]

Heat transfer factor [tex]\mu= 0.87.[/tex]

Generally the equation for  Power developed is mathematically given by

[tex]P=VI\\\\P=45*10^3*50*10^{-3}[/tex]

[tex]P=2.250[/tex]

Therefore

Power in area

[tex]P_a=1400*0.87[/tex]

[tex]P_a=1218watt[/tex]

Power Density

[tex]P_d=\frac{P_a}{Area}[/tex]

[tex]P_d=\frac{1218}{\pi(0.5^2/4)}[/tex]

[tex]P_d=6203.223062W/mm^2[/tex]

What is the frequency of a wavelength

Answers

the longer the wavelength, lower the frequency. In the same manner, shorter the wavelength, higher will be the frequency.

Wavelength is inversely proportional to frequency.

In an equation, wavelength is represented by the Greek letter lambda (λ). Depending on the type of wave, wavelength can be measured in meters, centimeters, or nanometers (1 m = 109 nm). The frequency, represented by the Greek letter nu (ν), is the number of waves that pass a certain point in a specified amount of time.

Hope this helps :))

Why is oiling done time and again in a sewing machine?

Answers

Answer:

to prevent friction on the surfaces

Answer:

Explanation:

Oiling reduces friction between parts with relative motion between them.

Repeated oiling is needed as the film of oil reducing the friction becomes thinner with time as some of the oil gets pushed off of the areas of motion where it can no longer be useful.

Oil also becomes oxidized which reduces the oil's ability to decrease friction.

Oil can also be fouled by dirt, lint or other material. This added material becomes coated in oil and typically gets sequestered away from the moving parts reducing the oil available for lubrication purposes.

1. A 5kg mass is hung by a vertical steel wire 0.5 m long and 6x 10 cm' in cross- I
sectional area. Hanging from the bottom of this mass is a similar steel wire, from
which in turn hangs a 10 kg mass. For each wire, compute (a) tensile strain and
(b) the elongation. The Young's modulus of steel is 2 x10" Pa.

Answers

Answer:

the answer is 9

Explanation:

because is 9

What is mechanical advantage?
O A. Output force divided by input force
O B. Input work divided by output work
O C. Output work divided by input work
O D. Input force divided by output force

Answers

Answer:

0A.Output force divided by input force.

Action and Reaction are equal in magnitude and opposite in direction.Then,Why do they not balance each other?​

Answers

Answer:

Newton's third law of motion states that every action has an equal and opposite reaction. This indicates that forces always act in pairs. Reaction forces are equal and opposite, but they are not balanced forces because they act on different objects so they don't cancel each other out.

What is science?Give two examples of living beings?

Answers

Answer:

the study of the past

Explanation:

dogs and cats

A ball of mass 0.50 kg is rolling across a table top with a speed of 5.0 m/s. When the ball reaches the edge of the table, it rolls down an incline onto the floor 1.0 meter below (without bouncing). What is the speed of the ball when it reaches the floor?


PLEASE EXPLAIN HOW YOU GOT THE ANSWER THANK YOU SO MUCH

Answers

Answer:

0

Explanation:

The speed of the ball when it reaches the floor is 0 because when an object is at rest or in uniform motion, it has no speed/velocity

The final speed of the ball when it reaches the floor is 7.10 m/s.

What is the conservation of energy?

The conservation of energy is a fundamental principle in physics that states that energy cannot be created or destroyed, but only converted from one form to another or transferred from one system to another. In other words, the total amount of energy in a closed system remains constant over time, even though it may be converted from one form to another.

This principle is based on the first law of thermodynamics, which states that the total energy of a closed system is always conserved, and can only be changed by the transfer of heat, work, or matter into or out of the system. The conservation of energy has important applications in various fields of physics, including mechanics, thermodynamics, and electromagnetism, and is a fundamental principle in the understanding of the natural world.

Here in the Question,

We can use the conservation of energy to solve this problem. Initially, the ball has kinetic energy due to its motion on the tabletop, but no potential energy since it is at a constant height. When the ball rolls off the edge of the table, it loses some kinetic energy due to friction but gains potential energy as it moves upward. When it reaches the floor, it has gained potential energy but lost kinetic energy due to friction. We can assume that the energy lost due to friction is converted to thermal energy, so the total energy of the system is conserved.

Let's start by calculating the potential energy gained by the ball as it moves from the edge of the table to the floor:

ΔPE = mgh

where ΔPE is the change in potential energy, m is the mass of the ball, g is the acceleration due to gravity, and h is the vertical distance traveled by the ball.

ΔPE = (0.50 kg)(9.81 m/s^2)(1.0 m) = 4.905 J

Now we can use the conservation of energy to find the final kinetic energy of the ball, which will allow us to calculate its final speed:

KEi + ΔPEi = KEf + ΔPEf

where KEi and ΔPEi are the initial kinetic and potential energies of the ball, respectively, and KEf and ΔPEf are the final kinetic and potential energies of the ball, respectively.

Since the ball is not bouncing, we can assume that its initial and final potential energies are zero. Therefore:

KEi = KEf + ΔKE

where ΔKE is the change in kinetic energy due to friction.

We can assume that the coefficient of kinetic friction between the ball and the incline is constant, and use the work-energy principle to find ΔKE:

Wfric = ΔKE

where Wfric is the work done by friction.

The work done by friction can be expressed as:

Wfric = ffricd

where ffric is the force of friction and d is the distance traveled by the ball on the incline.

The force of friction can be expressed as:

ffric = μmg

where μ is the coefficient of kinetic friction, and m and g have their usual meanings.

Putting it all together, we get:

KEi = KEf + ffricd

KEi = KEf + μmgd

(1/2)mv^2 = (1/2)mu^2 + μmgd

v^2 = u^2 + 2gd

where u is the initial speed of the ball on the tabletop, and v is the final speed of the ball on the floor.

Plugging in the given values, we get:

v^2 = (5.0 m/s)^2 + 2(9.81 m/s^2)(1.0 m)

v^2 = 50.405

v = 7.10 m/s

Therefore, the final speed of the ball when it reaches the floor is 7.10 m/s.

To learn more about  the Law of Conservation of Momentum click:

https://brainly.com/question/30487676

#SPJ2

State TRUE or FALSE.
1. We use muscular force to lift a bucket of water.
2. A bow uses mechanical force of the bow string to shoot an arrow.
3. The force of friction enables us to walk on earth.
4. Plants use solar energy to make their food.
5. The energy stored inside the earth is called atomic energy​

Answers

Answer:

1. True

2. False

3. True

4. True

5. True

Answer:

that is pure falsereeeeeeeee

Explanation:

Ashley, a psychology major, remarks that she has become interested in the study of intelligence. In other words, Ashley is interested in?

Answers

Group of answer choices.

a) the capacity to learn from experience, solve problems, and to adapt to new situations.

b) how behavior changes as a result of experience.

c) the factors directing behavior toward a goal.

d) the ability to generate novel

Answer:

a) the capacity to understand the world, think rationally, and use resources effectively.

Explanation:

Psychology can be defined as the scientific study of both the consciousness and unconsciousness of the human mind such as feelings, emotions and thoughts, so as to understand how it functions and affect human behaviors in contextual terms.

This ultimately implies that, psychology focuses on studying behaviors and the mind that controls it.

In this scenario, Ashley who is a psychology major, stated that she's interested in the study of intelligence.

Intelligence can be defined as a measure of the ability of an individual to think, learn, proffer solutions to day-to-day life problems and effectively make informed decisions.

In other words, Ashley is interested in the capacity of humans to understand the world, think rationally, and use resources effectively to produce goods and services that meet the unending requirements, needs or wants of the people (consumers or end users) living around the world.

If a jet travels 350 m/s, how far will it travel each second?

Answers

Answer:

It will travel 350 meters each second.

Explanation:

The unit rate, 350 m/s, tells us that the jet will travel 350 meters per every second elapsed.

Answer:

5.83 seconds

Explanation:

60 seconds in 1 minute

350 meters per second

350/60

=5.83

A wire carries a current of 0.66 A. This wire makes an angle of 58° with respect to a magnetic field of magnitude 5.50 10-5 T. The wire experiences a magnetic force of magnitude 7.10 10-5 N. What is the length of the wire?

Answers

Answer:

The length of the wire is "1.93 m".

Explanation:

Given:

Current,

I = 0.66 A

Angle,

[tex]\Theta[/tex] = 58°

Magnetic field of magnitude,

F = [tex]5.5\times 10^{-5}[/tex] N

The length of the wire will be:

⇒ [tex]F = B\times I\times L\times Sin \Theta[/tex]

or,

⇒ [tex]L = \frac{F}{B\times I\times Sin \theta}[/tex]

By putting the values, we get

       [tex]=\frac{5.5\times 10^{-5}}{0.66\times 5.1\times 10^{-5}\times Sin \ 58^{\circ}}[/tex]

       [tex]=\frac{5.5}{2.828}[/tex]

       [tex]=1.93 \ m[/tex]

State Newton's second law of motion ​

Answers

the acceleration of an object is directly related to the net force and inversely related to its mass

Explanation:

Newton's second law is a quantitative description of the changes that a force can produce on the motion of a body. It states that the time rate of change of the momentum of a body is equal in both magnitude and direction to the force imposed on it.

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