Neta 3 Exam pointers and questions

[Zepold72]

Also not sure how to solve this, somehow need to find real power first. Where does the 45 magnitude come in?

Can anyone help provide a solution?

Q=VxI Sin ɸ

Polar coordinates(r,θ) -----------------> Rectangular Coordinates ( r Sin θ, r Cos θ)
θ=10º ( 45 Sin 10º, 45 Cos 10º ) ===> ( 7.814167995, 44.31634889 )
r=45 ( x , y ) ===> ( x , y )
Tan θ = y/x
θ= Tan^-1 (y/x) = Tan ^-1 (44.31634889 / 7.814167995) = 80º

plug in all values

Q = 120 x 10 x Sin 80º = 1181.769304 VAR.

Even though none of the answers match i think this is the right answer.!!

[rsimmons]

Q=VxI Sin ɸ

Polar coordinates(r,θ) -----------------> Rectangular Coordinates ( r Sin θ, r Cos θ)
θ=10º ( 45 Sin 10º, 45 Cos 10º ) ===> ( 7.814167995, 44.31634889 )
r=45 ( x , y ) ===> ( x , y )
Tan θ = y/x
θ= Tan^-1 (y/x) = Tan ^-1 (44.31634889 / 7.814167995) = 80º

plug in all values

Q = 120 x 10 x Sin 80º = 1181.769304 VAR.

Even though none of the answers match i think this is the right answer.!!

The number you calculated is KVA not KVAR. Use the pyragorean theorem. Kva^2 = kw^2 + kvar^2. The mag*sine (theta) ×amps is the kvar = reactive power and not the apparent power in which you calculated. ( Those who read this, look up the power triangle and decide for yourselves)

[Zepold72]

Thanks rsimmons!! I realized it after I posted that I solved for the wrong power.

[lester mcmanaway]

so did you pass??