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2 years ago

What is Back EMF? How does it limits the speed of a permanent magnet DC?

Engineering

1 answer:

ss7ja [257]2 years ago

8 0

Answer and Explanation:

The DC motor has coils inside it which produces magnetic field inside the coil and due to thus magnetic field an emf is induced ,this induced emf is known as back emf. The back emf always acts against the applied voltage. It is represented by $E_b$

The back emf of the DC motor is given by $E_b=\frac{NP\Phi }{60A}$

Here N is speed of the motor ,P signifies the number of poles ,Z signifies the the total number of conductor and A is number of parallel paths

As from the relation we can see that back emf and speed ar dependent on each other it means back emf limits the speed of DC motor

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Which of the following justifies the need for an already-certified engineer to continue to take classes?

tatiyna

What are the answer choices?
Without the choices, I’d say so that they can further progress their engineering education. New technologies and new mechanical advancements are always coming out so it would be beneficial for the engineer to keep up to date by taking classes.

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2 years ago

The elastic settlement of an isolated single pile under a working load similar to that of piles in the group it represents, is p

Ganezh [65]

Answer:

The expected settlement for the pile group using the given information is 19.92mm or 0.79 inch

Explanation:

In this question, we are asked to calculate the expected settlement for the pole group given some information.

Please check attachment for complete solution and step by step explanation

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3 years ago

A saturated 1.5 ft3 clay sample has a natural water content of 25%, shrinkage limit (SL) of 12% and a specific gravity (GS) of 2

Svetllana [295]

$79 f t^{3}$ is the volume of the sample when the water content is 10%.

<u>Explanation:</u>

Given Data:

$V_{1}=100\ \mathrm{ft}^{3}$

First has a natural water content of 25% = $\frac{25}{100}$ = 0.25

Shrinkage limit, $w_{1}=12 \%=\frac{12}{100}=0.12$

$G_{s}=2.70$

We need to determine the volume of the sample when the water content is 10% (0.10). As we know,

$V \propto[1+e]$

$\frac{V_{2}}{V_{1}}=\frac{1+e_{2}}{1+e_{1}}$ ------> eq 1

$e_{1}=\frac{w_{1} \times G_{s}}{S_{r}}$

The above equation is at $S_{r}=1$ ,

$e_{1}=w_{1} \times G_{s}$

Applying the given values, we get

$e_{1}=0.25 \times 2.70=0.675$

Shrinkage limit is lowest water content

$e_{2}=w_{2} \times G_{s}$

Applying the given values, we get

$e_{2}=0.12 \times 2.70=0.324$

Applying the found values in eq 1, we get

$\frac{V_{2}}{100}=\frac{1+0.324}{1+0.675}=\frac{1.324}{1.675}=0.7904$

$V_{2}=0.7904 \times 100=79\ \mathrm{ft}^{3}$

7 0

3 years ago

If the load parameters are: Vln=600kV, Il=100A (resistive), calculate the source voltage and current when the line is 50Miles (s

Archy [21]

s 0Miles (short), 150 Miles(medium), and 300 Miles (long).

Explanation:

4 0

2 years ago

When designing a car that runs on wind or Air car . can you tell me the details for the following points Compressed Air Engine:

BabaBlast [244]

Answer:

The crack and connecting rod is used in the design of car.This mechanism is known as slider -crank mechanism.

Components:

1.Inlet tube

2. Wheel

3. Exhaust

4. Engine

5.Air tank

6.Pressure gauge

7.Stand

8. Gate valve

The efficiency of air engine is less as compare to efficiency of electric engine and this is not ecofriendly because it produce green house gases.These gases affect the environment.

it can run around 722 km when it is full charge.

5 0

3 years ago