EXAM question for PAST paper (1 Viewer)

[highshill]

https://thsconline.github.io/s/?view=6518&id=0ByEFYhkkDQBKbC03bkVEZnhjWWs&n=Sydney Grammar 2015 w. sol
I don't get question 23 (c)

I did Snell's Law:
sintheta2/sintheta1= n1/n2
sinr/sin30=1.00/1.5

1.00x1.2xsin30
sin[inverse](0.3333333....)= 19 degrees and 28 minutes

but the answers something else and I don't get the worked solution of that question, can someone please tell me were I went wrong.

And also 25 (a)
Thanks!

 

[Fizzy_Cyst]

23 (c) Seems like you have the refractive indicies the wrong way around

25(a) Determine voltage drop across parallel part (2x18 = 36V), then determine voltage drop across 8 Ohm resistor, keeping in mind that the currents through the individual parallel branches will combine (5 x 8 = 40V), voltage is therefore 36 + 40V = 76V

 

[highshill]

23 (c) Seems like you have the refractive indicies the wrong way around

25(a) Determine voltage drop across parallel part (2x18 = 36V), then determine voltage drop across 8 Ohm resistor, keeping in mind that the currents through the individual parallel branches will combine (5 x 8 = 40V), voltage is therefore 36 + 40V = 76V

Why did we ignore the 12 ohms resistor in question 25(a)?

 

[Fizzy_Cyst]

Why did we ignore the 12 ohms resistor in question 25(a)?

It's in parallel with the 18 ohm resistor and therefore they share the same voltage.

 

[highshill]

It's in parallel with the 18 ohm resistor and therefore they share the same voltage.

Oh, yes okay thanks a lot.