Engineering The components of a circuit with a voltage source and 2 resistors

[Hooke's Law]

Homework Statement

The components of a circuit with a voltage source and 2 resistors ( series ) has the following values vs = 10V, R1 = 100 , R2 = 150. With i1 leaving the +ve vs and i2 leaving -ve vs ( i.e. i1 entering node A, i2 is entering in the opposite direction of i1 )
Find:
a) Currents through each resistor
b) Voltages across each resistor
c)power dissipated by each resistor
d) power supplied by source
e)equivalent resistance seen by the source

Homework Equations

V=iR
P= iV

P-power
i- current
R- resistance

The Attempt at a Solution

4
Since the circuit is in series i1=i2=is
vs = v1 + v2
vs = isR(eq)

R(eq) = R1 + R2 = 250 ohms

vs / R(eq) = is ====> is = (10v)/(250 ohms) = 0.04A

v1 =isR1
v1 = (0.04 A)(100 ohms) = 4V

v2 = isR2
v2 = (0.04A)(150 ohms) = 6 V

P1= isv1
P1=(0.04A)(4v)=0.16W

P2 =isv2 = (0.04 A) (6V)= 0.24 W

Ps = isvs
Ps = 0.4W


Is there something wrong in my calculations or concept? & what does it mean by "e)equivalent resistance seen by the source"?

Thanks

 

[vk6kro]

The calculations look OK.

e) is just asking for the total resistance, which you already worked out.

In this case, it is obvious, but sometimes it is important to say which point you are looking from when you talk about input resistance.
So, they say "as seen by the power supply" as if the power supply could "see" what resistance was across it.