Complete Question
The complete question is shown on the first uploaded image
Answer:
a
The High Voltage Rating for Auto - Transformer is 86kV
The Low Voltage Rating for Auto - Transformer is 78kV
The MVA rating is 268.75
b
The efficiency is 99.4%
Explanation:
From the question we are given are given that
The transformer has Mega Volt Amp rating of 25MVA
The frequency is 60-Hz
Voltage rating 8.0kV : 78kV
The short circuit test gives : 453kV,321A,77.5kW
The open circuit test gives : 8.0kV, 39.6A, 86.2kW
This can be represented on a diagram shown on the second uploaded image
From this diagram we can deduce that the The High Voltage Rating for Auto - Transformer is 86kV and the Low Voltage Rating for Auto - Transformer is 78kV
Now to obtain the current flowing through the 8kV coil in the Auto-transformer we have
The volt will cancel each other
Now to obtain the required MVA rating we would multiply the value of Power obtained during the open circuit test by the value of the current calculated.we are making use of the power obtain during open circuit testing because the transformer at this point is not under any load.
We need to understand that Iron losses is due to open circuit test which has power = 86.2kW
While copper loss is due to short circuit test which has power = 77.5kW
The the current flowing through the secondary coil 
as shown in the circuit diagram can be obtained as
Now the efficiency can be obtained as thus
=99.941%
Answer:
Explanation:
My speed after the interaction will depend upon the impulse the ball will make on me . Now impulse can be expressed as follows
Impulse = change in momentum
change in momentum in the ball will be maximum when the ball bounces back with the same velocity which can be shown as follows
change in momentum = mv - ( - mv ) = 2mv
So when ball is bounced back with same velocity , it suffers greatest impulse from my hand . In return , it reacts with the same impulse on my hand pushing me with greatest impulse according to third law of motion. this maximizes my speed after the interaction.
First question (upper left):
1/Req = 1/12 + 1/24 = 1/8
Req = 8 ohms
Voltage is equal through different resistors, and V1 = V2 = 24 V.
Current varies through parallel resistors: I1 = V1/R1 = 24/12 = 2 A. I2 = 24/24 = 1 A.
Second question (middle left):
V1 = V2 = 6 V (parallel circuits)
I1 = 2 A, I2 = 1 A, IT = 2+1 = 3 A.
R1 = V1/I1 = 6/2 = 3 ohms, R2 = 6/1 = 6 ohms, 1/Req = 1/2 + 1/1, Req = 2/3 ohms
Third question (bottom left):
V1 = V2 = 12 V
IT = 3 A, meaning Req = V/It = 12 V/3 A = 4 ohms
1/Req = 1/R1 + 1/R2, 1/4 = 1/12 + 1/R2, R2 = 6 ohms
I1 = V/R1 = 1 A, I2 = V/R2 = 2 A
Fourth question (top right):
1/Req = 1/20 + 1/20, Req = 10 ohms
IT = 4 A, so VT = IT(Req) = 4*10 = 40 V
Parallel circuits, so V1 = V2 = VT = 40 V
Since the resistors are identical, the current is split evenly between both: I1 = I2 = IT/2 = 2 A.
Fifth question (middle right):
1/Req = 1/5 + 1/20 + 1/4, Req = 2 ohms
IT = VT/Req = 40 V/2 ohms = 20 A
V1 = V2 = V3 = 40 V
The current of 20 A will be divided proportionally according to the resistances of 5, 20, and 4, the factors will be 5/(5+20+4), 20/(5+20+4), and 4/(5+20+4), which are 5/29, 20/29, and 4/29.
I1 = 20(5/29) = 100/29 A
I2 = 20(20/29) = 400/29 A
I3 = 20(4/29) = 80/29 A
Sixth question (bottom right):
V2 = 30V is given, but since these are parallel circuits, V1 = VT = 30 V.
Then I1 = V1/R1 = 30 V/10 ohms = 3 A.
I2 = 30 V/15 ohms = 2 A.
IT = 3 + 2 = 5 A
1/Req = 1/10 + 1/15, Req = 6 ohms
The bending of light rays is the result of refraction of light passing through the lens. A converging lens is curved on both sides such that the rays coming out of it come together at a point (converge). The point at which the right rays meet after refraction is called the focal point which is a real in the convex lens.
Answer:
static
Explanation:
static friction pushes in the direction you are walking.
