8. Ella wants to replace old bulbs of her home with new LED bulbs. She buys LED bulb that has inbuilt AC to DC converter of output 5V and 2.5A. a. If the LED is 75% efficient, what would be the power dissipated? b. Find the work done by the LED when it is connected to the power supply and left for 1hour 15 minutes.​

Answers

Answer 1

The power dissipated by the LED is 20 Watts and the work done for 1 hour 15 minutes is 56.25 kJ.

What is electrical power?

Electrical power is the rate at which electrical work is done.

Electrical power = voltage × current

The LED is 75% efficient means that 75% of power dissipated by the LED is converted to light.

Total power dissipated = 5 × 2.5 = 12.5 Watts

Work done = power × time (in seconds)

Work done = 12.5 × (1 × 3600 + 15 × 60)

Work done = 56250 J = 56.25 kJ

Therefore, the power dissipated by the LED is 20 Watts and the work done for 1 hour 15 minutes is 56.25 kJ.

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Related Questions

Calculate the current through the ammeter (look at photo)

Answers

Answer:

6 amps

Explanation:by Kirchhoff's loop rule the current at any point in the loop must be equal or charge would be building up. The current at the ammeter is equally to the total current through the sun of the paths in parallel which it is in series with

Calculate the force on a unit positive charge at p on x axis whose co-ordinates are (x=2m,y=0) due to the following two charges 1. A positive charge of 10−9C situated in air at the origin (X=0,y=0). 2. A negative charge of -2*10−9C situated on X axis(x=1m, y=0

Answers

The force on a unit positive charge at the given position is determined as 1.8 x 10⁻⁸ N.

Force on the charge

The force on the charge is calculated as follows;

F = k(q1q2)/r²

where;

r is the distance between the charges = 2 m - 1m = 1m

F = (9 x 10⁹ x 10⁻⁹ x 2 x 10⁻⁹)/(1)²

F = 1.8 x 10⁻⁸ N

Thus, the force on a unit positive charge at the given position is determined as 1.8 x 10⁻⁸ N.

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CFCs were found to destroy what important compound in our atmosphere?

Answers

CFCs were found to destroy the important compound in our atmosphere which is called as the Ozone layer.

What are CFCs?

The CFCs are called as the Chloro Fluoro carbon are the fuels used in the jet flights long time ago.

The ozone layer protects the harmful UV rays coming from the Sun to reach the Earth's surface. This layer was depleted by the use of CFCs which consist of harmful element Chlorine in large amount.

This has developed a hole in ozone layer over Antarctica. Global warming is the greatest consequence of the depletion of ozone layer.

Thus, CFCs found to destroy ozone layer.

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3. Two wires increase in length by the same amount when both their temperatures increase by the same amount, as shown in the diagram. Before the temperature increase, the longer wire is 1.2525 m long. The shorter wire’s linear coefficient of thermal expansion is 1.135 times that of the longer wire. How much shorter is the shorter wire before the temperature increase? Answer to three significant figures
Viết cho Ngọc Khánh

Answers

Two wires increase in length by the same amount when both their temperatures increase by the same amount, the shortness of the wire before the temperature increase is mathematically given as

dL=0.1485m

How much shorter is the shorter wire before the temperature increase?

Generally, the equation for change in length is mathematically given as

[tex]dl=lo \alpha dt[/tex]

Therefore

dl1=dl2

Where

a2=1.35a1

Hence

a1l1dt= a2l2dt

a1(1.2525)= a1*(1.135)(l2)

L2=1.104m

In conclusion, a change in length due to temperature is

dL=1.2525-1.104m

dL=0.1485m

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Why is digital forensics important?

Answers

Hi! digital forensics is important because not only does digital forensics allow cyber security organisations to develop technologies that can prevent hackers from accessing devices, websites and networks but can lead businesses in the direction of understanding exactly what data is compromised.

which two forces operate over only very SHORT distances?
A. weak nuclear and gravitational
B. strong nuclear and gravitational
C. weak nuclear and electromagnetic
D. strong nuclear and weak nuclear

Answers

Strong nuclear and weak nuclear forces act only over short range distances.

What are forces?

Forces are agents which bring about a change in the state or motion of an object.

Forces can be described as pull or push agents.

Forces can either be contact or non-contact forces.

Some non-contact forces are gravitational forces and nuclear forces.

Nuclear forces act only over short range distances. Example are the strong and weak nuclear forces.

Therefore, strong nuclear and weak nuclear forces act only over short range distances.

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Study the image.

Which of the following choices best explains how the lever made the task easier?

The final force on the rock was the same as the original force from the person and the distance the rock traveled was smaller than the original distance the lever moved, so the total work decreased.

The final force on the rock was greater than the original force from the person and the distance the rock traveled was smaller than the original distance the lever moved, but the total work remained the same.

The final force on the rock was smaller than the original force from the person and the distance the rock traveled was greater than the original distance the lever moved, so the total work stayed the same.

The final force on the rock was greater than the original force from the person and the distance the rock traveled was the same as the original distance the lever moved, so the total work increased.

Answers

The final force on the rock was smaller than the original force from the person and the distance the rock traveled was greater than the original distance the lever moved, so the total work stayed the same.

What is the law of conservation of energy?

The law of conservation of energy states that energy can neither be created nor destroyed but can be transformed from one form to another.

The total work done on the process will be conserved.

The lever is a simple machine which makes work easier by reducing the force applied to the load and increasing the distance traveled by the load.

Thus, the final force on the rock was smaller than the original force from the person and the distance the rock traveled was greater than the original distance the lever moved, so the total work stayed the same.

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Why is the contribution of the wavelets lying on the back of secondary wave front zero?​

Answers

Answer:

The contribution of the wavelets lying on the back of the wave front is zero because of something known as the Obliquity Factor. It is assumed that the amplitude of the secondary wavelets is not independent of the direction of propagation, Sources: byju's.com

According to the Voigt and Kirchhoff's law for wavelets, the contribution of a wavelet in any direction making an angle x with the normal to the wavelet is proportional to {1+cos(x)/2)}

For wavelet lying on the back of secondary wavefront,

x = 180°

→ So, the proportional factor:

→ {1+cos(180°)/2}

→ (1-1/2)

→ (0/2)

→ 0

That's why the contribution of the wavelets lying on the back of secondary wave front is zero

Question: What are phases of the moon. What evidence can you provide to explain how the moon revolution determines its shape?

Think!!!! Write Claim, Reasoning and add evidence

Answers

Answer:

Claim: The phases of the Moon progress from new moon to crescent moon, first-quarter moon, gibbous moon, and full moon as the Moon waxes (the amount of illumination is increasing from Earth). As the moon revolves around Earth, its sunlit surface is visible in different portions as it reveals its phases.

 Evidence: As the moon revolves around Earth, different parts of the sunlit surface of the moon can be seen. As a result, the moon's appearance changes from night to night from Earth's perspective. The moon's apparent shape changes, as well as its position in the sky.

Reasoning: Over the course of two weeks, the moon's entire appearance changes, from a bright circle to a circle sliced in half and finally to nothing.

Hope this helps you czn!!

Please Mark me Brainleast if am correct!!

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Answer:

Claim: The phases of the Moon progress from new moon to crescent moon, first-quarter moon, gibbous moon, and full moon as the Moon waxes (the amount of illumination is increasing from Earth). As the moon revolves around Earth, its sunlit surface is visible in different portions as it reveals its phases.

Evidence: As the moon revolves around Earth, different parts of the sunlit surface of the moon can be seen. As a result, the moon's appearance changes from night to night from Earth's perspective. The moon's apparent shape changes, as well as its position in the sky.

Reasoning: Over the course of two weeks, the moon's entire appearance changes, from a bright circle to a circle sliced in half and finally to nothing.

Hope this helps you czn!!

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If the period of a wave is 9.2 s, what is its frequency (in Hz)?

Answers

The period of the function is the inverse of the frequency:

 ⇒ (in other words) [tex]period = \frac{1}{frequency}[/tex]

Since the period is 9.2s:

 [tex]Frequency = \frac{1}{period}=\frac{1}{9.2} =0.11_.Hz[/tex]

Answer: 0.11 Hz

Hope that helps!

Discuss how wind energy was used in ancient times.

Answers

Answer:

People used wind energy to propel boats along the Nile River as early as 5,000 BC. By 200 BC, simple wind-powered water pumps were used in China, and windmills with woven-reed blades were grinding grain in Persia and the Middle East.

Explanation:

Hope it helps you:)))))

have a good day

Calculate 9 ∙ 10-5 divided by 3 ∙ 10-9. (Box after the "10" in answer is for the exponent.). ∙ 10 .

Answers

The result of 9 ∙ 10-⁵ divided by 3 ∙ 10-⁹ is 3 × 10⁴. Details about exponential functions can be found below.

How to calculate multiplication involving exponentiation?

Exponentiation is the process of calculating a power by multiplying together a number of equal factors, where the exponent specifies the number of factors to multiply.

According to this question, the following exponential function is given:

9 × 10-⁵ ÷ 3 × 10-⁹

9/3 × 10-⁵+⁹

3 × 10⁴

Therefore, the result of 9 ∙ 10-⁵ divided by 3 ∙ 10-⁹ is 3 × 10⁴.

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If two balls have the same volume, but ball A has twice as much mass as ball B, which one will have the greater density?

Answers

Answer:

A

Explanation:

Density is    mass/ volume    

     if the numerator is greater ( A) then the density is greater than B

What is the equivalent resistance of a circuit that contains two 50.00
resistors connected in series with a 12.0 V battery?
Ο A. 0.120 Ω
Ο Β. 100.0 Ω
OC. 0.480
OD. 25.00

Answers

Answer:

B

Explanation:

Resistors in series add because there is only one path the current can take.

calculations

= R1 + R2

= 50 + 50

= 100

3. Harris is putting in a three-phase Y-Y-
connected transformer bank and the
secondary line-to-line voltage is 208 V.
What's the line-to-neutral voltage?
O A. 120 V
O B. 359 V
C. 69 V
O D. 240 V

Answers

120V is the line-to-neutral voltage .

What is Line Voltage ?

It is defined as the voltage of a power transmission circuit or distribution circuit up to the point of transformation or utilization.

The secondary line voltage is [tex]V_{L} = 280 V[/tex]

The notation AC indicates that the current is an alternating current.

The given formula is [tex]V_{ph} = \frac{V_{L} }{\sqrt{3} }[/tex]

Substitute  208 V into the formula

[tex]V_{ph} = \frac{V_{L} }{\sqrt{3} } \\\\V_{ph} = \frac{208V}{\sqrt{3} } \\\\= 120 (Approx)[/tex]

So, the line-to-neutral voltage is 120 V.

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A duck has a mass of 2.70 kg. As the duck paddles, a force of 0.110 N acts on it in a direction due east. In addition, the current of the water exerts a force of 0.220 N in a direction of 47.0° south of east. When these forces begin to act, the velocity of the duck is 0.120 m/s in a direction due east. Find (a) the magnitude and (b) the direction (relative to due east) of the displacement that the duck undergoes in 2.70 s while the forces are acting. (Note that the angle will be negative in the south of east direction.)

Answers

a) The magnitude will be 0.838m

b) The displacement will be -17.35°

What is displacement?

The path covered by an object from its initial point to final point.

Forces acting on the duck

x-axis:    0.13 + 0.16*cos(-56°) = 2.7 * ax  

ax = 0.0813 m/s^2

y-axis:    0.13*sin(-56°) = 2.7 * ay  

ay = -0.0491 m/s^2

The displacement on the x-axis

X = Vox * t + ax/2 * t²

X = 0.12* 3.2 + 0.0813/2*3.2²

X = 0.8

The displacement on the y-axis:

Y = Voy * t + ay/2 * t²

X = 0 - 0.0491/2*3.2²

Y=-0.25m

So, the magnitude and angle of this displacement [0.8,-0.25] is:

0.838m  at an angle of -17.35°

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What are you and the Australian Institute of Marine Biology trying to find out and 4. Why might it be important to find this information out

Answers

Answer:

Established in 1972 by the McMahon Government, the institute's primary function is research for sustainable use and protection of the marine environment. The Institute investigates topics from broad-scale ecology to microbiology.

A car starts from rest and coasts down a hill with a constant acceleration.If it goes 90m in 8s,find the acceleration and velocity after 8s.​​​

Answers

speed or velocity= s/t => 90m/8s = 11.25 m/s => a= change in speed / change in time => 11.25 m/s / 8s = 1.4 m/s^2

A 5.0 kg box is sitting on a scale in an elevator. Before the elevator moves, the scale reads 49.05 N. When the elevator accelerates into motion, the scale momentarily reads 46.75 N. If the acceleration due to gravity is 9.81 m/s2, what is the magnitude of the acceleration of the elevator? (1 point)

A) 0.46 m/s2
B) 0.57 m/s2
C) 0.87 m/s2
D) 0.91 m/s2

Answers

The magnitude of acceleration of the elevator is 0.46m/s². Details on how to calculate magnitude of acceleration can be found below.

How to calculate magnitude of acceleration?

The magnitude of acceleration of the accelerator can be calculated by dividing the difference in force by the mass of the accelerator.

According to this question, a 5.0 kg box is sitting on a scale in an elevator. Before the elevator moves, the scale reads 49.05 N, however, when the elevator accelerates into motion, the scale momentarily reads 46.75 N.

Magnitude of acceleration = (49.05 - 46.75)/5

Magnitude of acceleration = 2.3/5

Magnitude of acceleration = 0.46m/s²

Therefore, the magnitude of acceleration of the elevator is 0.46m/s².

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Why is the human population unique in its ability to affect the environment?
Our population is very large.
We use a lot of resources.
Our population is growing quickly.
All of the above.

Subect: science (not sure if this means pyhsics or chemistry)

Answers

Answer:

All of the above

Explanation:

hope it helps you

Why would you expect a person with impairment of the organs of equilibrium to become more unsteady when the eyes are closed?

Answers

Answer:

A person with impairment of organs of equilibrium would compensate for their lack of sensory information by their eyes therefore if their eyes are closed they aren't able to sense their location in space accurately (Proprioception)

Explanation:

Three sticks are arranged to form a right triangle. If the lengths of the three sticks are 0.47 m, 0.62 m and 0.78 m, what are the three angles of the triangle?

Answers

The angles in the triangle are 91 degrees, 53 degrees and 36 degrees respectively.

What is the cosine rule?

From the cosine rule we know that;

c^2 = a^2 + b^2 - 2abcosC

Since;

a = 0.47 m

b =  0.62 m

c =  0.78 m

Then;

(0.78)^2 = (0.47)^2 + (0.62)^2 - 2(0.47 * 0.62)cosC

0.61 = 0.22 + 0.38 - 0.58 cosC

0.61 - ( 0.22 + 0.38) = - 0.58 cosC

0.01 = - 0.58 cosC

C = cos-1(0.01/-0.58)

C = 91 degrees

Using the sine rule;

b/Sin B = c/Sin C

0.62/sinB = 0.78/sin 91

0.62/Sin B = 0.78

B = sin-1 (0.62//0.78)

B = 53 degrees

Angle A is obtained from the sum of angles in a triangle;

180 - (91 + 53)

A = 36 degrees

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An aircraft lands and brakes, slowing from 250 m/s to 5 m/s in 30 secs. What is it's acceleration?
O-10 m/s²
-8.2 m/s²
-1.3 m/s²
-5.2 m/s²

Answers

The acceleration of the aircraft is determined as -8.2 m/s².

Acceleration of the aircraft

The acceleration of the aircraft is calculated as follows;

a = Δv/t

where;

Δv is change in velocityt is time

a = (5 - 250)/(30)

a = -8.2 m/s²

Thus, the acceleration of the aircraft is determined as -8.2 m/s².

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Question 6 of 10
Which statements below are true?
Check all that apply.
A. Displacement measurements must include magnitude, unit, and
direction.
B. If motion starts and stops at the same location, then the
displacement is zero.
C. Distance can be fully described with a magnitude and a unit.
D. Distance is always less than or equal to the magnitude of the
displacement.

Answers

Answer:

A, AND B,

Explanation: just trust me bro

The rubber band contains .......potential energy as it is stretched.

less

more

same

Answers

Answer:

elastic potential energy

You input potential (stored) energy into the rubber band system when you stretched the rubber band back. Because it is an elastic system, this kind of potential energy is specifically called elastic potential energy.

Explanation:

An object is placed 4.0 cm to the left of a convex lens with a focal length of +8.0 cm . Where is the image of the object?

Answers

The image of the object is 8cm to the left of the lens (D)

What is the image of an object?

The image of an object is said to be the location where light rays from that object intersect with a mirror by reflection.

It is calculated thus:

1÷v = 1÷f - 1÷u

How to calculate the image of an object

From the formula

1÷v = 1÷f - 1÷u

Where

V = image distance fromthe object

U = object

f = focal length

Substitute the values

1÷v = 1÷8 - 1÷ 4

1÷v = - 1÷8

Make v the subject of formula

v = -8cm

Therefore, the image of the object is 8cm to the left of the lens (D)

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ten-story building has identical stairs throughout its stairways. A student calculates the amount of work required to climb one set of stairs and the amount of work to climb the entire ten sets.


Which quantity will remain constant in this experiment?

Answers

Answer:

c

Explanation:

Define 1 volt. Express it in terms of SI unit of work and charge calculate the amount of energy consumed in carrying a charge of 1 coulomb through a battery of 3 V.​

Answers

Answer:

Work done =3 joules

Explanation:

1 volt is the same as 1 Coulomb and 1 Joule

V=W/Q

1=W/3

W=3 x 1

W=3 Joules

According to the law of conservation of energy, which changes would INCREASE the total energy of a system?
A. An addition of 400 J of thermal energy and a loss of 550 J of kinetic energy
B. An addition of 200 J of thermal energy and a loss of 550 J of thermal energy
C. An addition of 300 J of GPE and a loss of 450 J of thermal energy
D. An addition of 500 J of kinetic energy and a loss of 450 J of thermal energy

Answers

The changes that would increase the total energy of a system is an addition of 500 J of kinetic energy and a loss of 450 J of thermal energy.

What is conservation of energy?

The term conservation of energy means that energy can not be created nor destroyed.

In this case, the changes that would increase the total energy of a system is an addition of 500 J of kinetic energy and a loss of 450 J of thermal energy.

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Is the following chemical reaction balanced?
2H₂O2H₂O + 0₂

yes
no

Answers

yes it is a chemical reaction
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